Rounding to the nearest 10 bingo
Rounding to the nearest 10 bingo uses 99 problems (every number from 1 to 99, rounded to the nearest ten), whose 11 different answers fill 3x3 cards. The caller reads "92 to the nearest 10", players mark 90. With 30 cards a line falls by call 3, so play for a full card (first one at call 19).
50 | 90 | 100 |
60 | 10 | 70 |
30 | 0 | 80 |
The caller reads a problem; players mark its answer. 99 problems, 11 answers.
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Caller sheet
Every call in a shuffled order. Tick each one as you read it out; the same share link always gives the same order.
Updated
Rounding to the nearest 10 at a glance
| What is called | 99 problems: every number from 1 to 99, rounded to the nearest ten |
|---|---|
| What is on the cards | 11 answers, from 0 to 100 |
| Recommended card | 3x3: 9 answers per card |
| Different cards possible | 19,958,400 (11 answers placed in 9 squares) |
| Typical level | Grade 3 |
| Problems per answer | 4 to 10 |
Answer key: every rounding to the nearest 10 problem by answer
99 calls, 11 squares. First marked = (99 + 1) ÷ (problems + 1), the average call at which the answer is reached in a shuffled game.
| Answer | Problems the caller reads | Problems | First marked (avg. call) |
|---|---|---|---|
| 0 | 1 to the nearest 10, 2 to the nearest 10, 3 to the nearest 10, 4 to the nearest 10 | 4 | 20 |
| 10 | 5 to the nearest 10, 6 to the nearest 10, 7 to the nearest 10, 8 to the nearest 10, 9 to the nearest 10, 10 to the nearest 10, 11 to the nearest 10, 12 to the nearest 10, 13 to the nearest 10, 14 to the nearest 10 | 10 | 9.1 |
| 20 | 15 to the nearest 10, 16 to the nearest 10, 17 to the nearest 10, 18 to the nearest 10, 19 to the nearest 10, 20 to the nearest 10, 21 to the nearest 10, 22 to the nearest 10, 23 to the nearest 10, 24 to the nearest 10 | 10 | 9.1 |
| 30 | 25 to the nearest 10, 26 to the nearest 10, 27 to the nearest 10, 28 to the nearest 10, 29 to the nearest 10, 30 to the nearest 10, 31 to the nearest 10, 32 to the nearest 10, 33 to the nearest 10, 34 to the nearest 10 | 10 | 9.1 |
| 40 | 35 to the nearest 10, 36 to the nearest 10, 37 to the nearest 10, 38 to the nearest 10, 39 to the nearest 10, 40 to the nearest 10, 41 to the nearest 10, 42 to the nearest 10, 43 to the nearest 10, 44 to the nearest 10 | 10 | 9.1 |
| 50 | 45 to the nearest 10, 46 to the nearest 10, 47 to the nearest 10, 48 to the nearest 10, 49 to the nearest 10, 50 to the nearest 10, 51 to the nearest 10, 52 to the nearest 10, 53 to the nearest 10, 54 to the nearest 10 | 10 | 9.1 |
| 60 | 55 to the nearest 10, 56 to the nearest 10, 57 to the nearest 10, 58 to the nearest 10, 59 to the nearest 10, 60 to the nearest 10, 61 to the nearest 10, 62 to the nearest 10, 63 to the nearest 10, 64 to the nearest 10 | 10 | 9.1 |
| 70 | 65 to the nearest 10, 66 to the nearest 10, 67 to the nearest 10, 68 to the nearest 10, 69 to the nearest 10, 70 to the nearest 10, 71 to the nearest 10, 72 to the nearest 10, 73 to the nearest 10, 74 to the nearest 10 | 10 | 9.1 |
| 80 | 75 to the nearest 10, 76 to the nearest 10, 77 to the nearest 10, 78 to the nearest 10, 79 to the nearest 10, 80 to the nearest 10, 81 to the nearest 10, 82 to the nearest 10, 83 to the nearest 10, 84 to the nearest 10 | 10 | 9.1 |
| 90 | 85 to the nearest 10, 86 to the nearest 10, 87 to the nearest 10, 88 to the nearest 10, 89 to the nearest 10, 90 to the nearest 10, 91 to the nearest 10, 92 to the nearest 10, 93 to the nearest 10, 94 to the nearest 10 | 10 | 9.1 |
| 100 | 95 to the nearest 10, 96 to the nearest 10, 97 to the nearest 10, 98 to the nearest 10, 99 to the nearest 10 | 5 | 16.7 |
Self-check: rounding to the nearest 10 answers
- 2 rounds to 0
- 9 rounds to 10
- 21 rounds to 20
- 28 rounds to 30
- 35 rounds to 40
- 47 rounds to 50
- 61 rounds to 60
- 69 rounds to 70
- 80 rounds to 80
- 90 rounds to 90
- 98 rounds to 100
Why some rounding to the nearest 10 squares fill first
The 99 problems in rounding to the nearest 10 bingo produce only 11 different answers, 9 problems per answer on average. 9 of the 11 answers are reached by 10 problems each; 0 by 4 problems only.
So squares are not equal: an answer with 10 problems is first marked around call 9.1, one with 4 around call 20. After 25 calls, 10 has a 95% chance of being marked against 69% for 0.
For a fairer game, call one problem per answer (11 calls instead of 99); for practice, calling every problem gives the class more repetitions of the facts behind 10.
How long a rounding to the nearest 10 game lasts
300 simulated rounding to the nearest 10 games (3x3, any line wins): 1 card needed 8 calls (median), 10 cards 4, 30 cards 3, with 8 in 10 games between call 3 and 5.
A class of 30 playing rounding to the nearest 10 bingo uses 3% of the 99 calls per game, so one caller sheet covers about 33 games; 3x3 cards from 11 answers overlap so much that lines fall almost at once, so play for a full card (all 9 squares) instead, which took a median of 19 calls with 30 cards.
How to play rounding to the nearest 10 bingo in class
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Model one call
Work through 83 to the nearest 10 → 80 on the board and 20 to the nearest 10 → 20, so everyone sees what a call sounds like and which square it marks.
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Hand out the cards
Print 3x3 rounding to the nearest 10 cards: 9 of the 11 answers (0 to 100) each, 82% coverage.
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Read the problem, not the answer
Call "20 to the nearest 10", pause, then the next. 0 has only 4 problems, so its square fills late.
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Check every bingo
Read back the called problems; the winner names each answer (83 to the nearest 10 → 80). 30 cards: first bingo near call 3.
Example calls from this set
Four problems drawn from the rounding to the nearest 10 caller sheet and the square each one marks.
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The caller reads 89 to the nearest 10
Mark 90 (also reached by 85 to the nearest 10, 86 to the nearest 10, 87 to the nearest 10 and 6 more)
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The caller reads 42 to the nearest 10
Mark 40 (also reached by 35 to the nearest 10, 36 to the nearest 10, 37 to the nearest 10 and 6 more)
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The caller reads 61 to the nearest 10
Mark 60 (also reached by 55 to the nearest 10, 56 to the nearest 10, 57 to the nearest 10 and 6 more)
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The caller reads 6 to the nearest 10
Mark 10 (also reached by 5 to the nearest 10, 7 to the nearest 10, 8 to the nearest 10 and 6 more)
Frequently asked questions
How many problems are in rounding to the nearest 10 bingo?
99 problems (every number from 1 to 99, rounded to the nearest ten), with 11 different answers. The caller sheet lists all 99; the cards show only the answers.
What size card works best for rounding to the nearest 10?
3x3. A card needs 9 different answers and the rounding to the nearest 10 set has 11 (0 to 100), so a 3x3 card is the largest that fits. That still allows 19,958,400 different cards.
Which answers come up most often?
9 of the 11 answers are reached by 10 problems each (10: 5 to the nearest 10, 6 to the nearest 10, 7 to the nearest 10, 8 to the nearest 10, 9 to the nearest 10 and 5 more), so their squares are first marked around call 9.1 on average; 0 with 4 problems waits until about call 20.
How many calls until someone wins?
In 300 simulated rounding to the nearest 10 games with 30 3x3 cards, the first line was completed after a median of 3 calls; with 10 cards after 4 calls.
Related
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