To compare two-digit numbers, think about tens and ones.
| Sign | We say | Example |
|---|---|---|
| $<$ | is less than | $29 < 31$ |
| $>$ | is greater than | $31 > 29$ |
| $=$ | is equal to | $40 = 40$ |
Key idea
Compare the tens first. Only if the tens are the same, compare the ones.
Why it works
One ten is more than any number of loose ones, because a number can have at most 9 ones. So more tens always means a greater number.
Worked example: Different tens
Compare 46 and 64.
- 46 has 4 tens. 64 has 6 tens.
- 6 tens is more.
- $46 < 64$
Answer: $46 < 64$
Worked example: Same tens
Compare 57 and 52.
- Both have 5 tens.
- Compare the ones: 7 is more than 2.
- $57 > 52$
Answer: $57 > 52$
Common mistake
Comparing the ones first and saying $29 > 31$, or mixing up $<$ and $>$. Compare tens first. The open side of the sign faces the greater number.
For grown-ups: Draw the signs as a hungry mouth that opens toward the bigger number, then check with tens and ones.