What pattern do you notice when comparing 21, 31, 41, 51, and 61?
AThe ones digit changes each time while the tens name stays the same
BThe tens name changes but the ones digit stays the same
CAll of these numbers are multiples of 10
DThe numbers skip by 5 each time
In 21, 31, 41, 51, 61, the tens name changes (twenty, thirty, forty, fifty, sixty) but the ones digit is always 1. This is the key pattern: the same ones digits (1–9) repeat in every group of ten, with only the tens name changing at the front. This pattern is what makes counting to 100 learnable without memorizing every number individually.
Question 2 Multiple Choice
Maria has learned to count to 29. Her friend says she now needs to memorize 71 entirely new numbers to reach 100. Is her friend right?
AYes — every number from 30 to 100 uses a completely new pattern
BNo — she only needs to learn 7 new tens names; then the same ones-digit pattern repeats
CNo — she already knows all 100 numbers just from counting to 29
DYes — counting to 100 requires learning a different set of rules for each decade
Maria's friend is wrong. She already knows the ones-digit sequence (1–9) from counting to 29. The only new things to learn are 7 tens names: thirty, forty, fifty, sixty, seventy, eighty, ninety. After that, the same pattern repeats: thirty-one, thirty-two... just like twenty-one, twenty-two. This is the power of the pattern — it dramatically reduces what needs to be memorized.
Question 3 True / False
The numbers 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100 can be thought of as 'landmark numbers' — the end of each group of ten.
TTrue
FFalse
Answer: True
True. These round tens are the boundary points in the count to 100. Each marks the completion of a full group of ten. Recognizing them as landmarks helps students navigate the counting sequence — they know that after 39 comes 40, after 59 comes 60, and so on. These are also the first numbers where you see only a tens digit (and no ones digit above zero).
Question 4 True / False
After learning to count to 29, a student should learn a mostly new pattern for the numbers 30 through 39.
TTrue
FFalse
Answer: False
False. The pattern for 30–39 (thirty-one, thirty-two... thirty-nine) is identical to the pattern for 20–29 (twenty-one, twenty-two... twenty-nine). Only the tens name changes. The student already knows the ones-digit rhythm; she just attaches 'thirty' to the front instead of 'twenty.' This is exactly why the pattern makes counting to 100 manageable.
Question 5 Short Answer
Explain in your own words why the repeating tens pattern makes counting to 100 much easier than having to memorize 100 separate number names.
Think about your answer, then reveal below.
Model answer: Once you know the nine ones digits (one through nine) and the seven tens names (thirty through ninety), the same pattern repeats in every group: thirty-one, thirty-two... just like twenty-one, twenty-two. You only need to learn the tens names — the rest follows automatically from the pattern you already know.
The base-ten system creates a predictable, repeating structure. Instead of 100 arbitrary labels, there are 9 ones digits and 9 tens names that combine to produce all the numbers from 1 to 99. This is not just a convenience trick — it is a preview of how the entire place value system works. Every larger number is built from the same principle of combining positional values.