Adding & Subtracting 10 - 1st Grade Math

1. Find and correct the error: A student says $10$ more than $65$ is $66$.

   Correct answer: $75$. Student only added $1$; should change tens digit.

2. Which number is $10$ more than $26$: $16$, $36$, or $46$?

   $36$. Only $36$ has tens digit one more than $26$'s.

3. What is $10$ more than $40$?

   $50$. $40 + 10 = 50$ because the tens digit increases from $4$ to $5$.

4. What is $10$ more than $41$?

   $51$. Increase tens digit from $4$ to $5$.

5. Identify the missing number: $47 + 10 = \square$.

   $57$. Add $10$ to $47$ by increasing tens digit to $5$.

6. What is $10$ less than $19$?

   $9$. $19 - 10 = 9$ because we go from $1$ ten to $0$ tens.

7. What is $10$ more than $60$?

   $70$. Change the tens digit from $6$ to $7$, keep ones digit $0$.

8. What is $10$ less than $70$?

   $60$. $70 - 10 = 60$ because the tens digit decreases from $7$ to $6$.

9. What is $10$ less than $58$?

   $48$. $58 - 10 = 48$ because the tens digit decreases from $5$ to $4$.

10. What is $10$ less than $34$?

    $24$. $34 - 10 = 24$ because the tens digit decreases from $3$ to $2$.

11. Identify the number that is $10$ more than $34$.

    $44$. Change the tens digit from $3$ to $4$, keep ones digit $4$.

12. What is $10$ more than $99$?

    $109$. $99 + 10 = 109$ because we need to regroup into hundreds.

13. Which number is $10$ less than $62$: $42$, $52$, or $72$?

    $52$. Only $52$ has tens digit one less than $62$'s.

14. Identify the number that is $10$ more than $26$.

    $36$. $26 + 10 = 36$ because the tens digit increases from $2$ to $3$.

15. Which digit changes when you add $10$ to a two-digit number?

    The tens digit increases by $1$. Adding $10$ adds one group of ten, changing only the tens place.

16. What is $10$ less than $47$?

    $37$. Change the tens digit from $4$ to $3$, keep ones digit $7$.

17. Find and correct the error: A student says $10$ less than $40$ is $39$.

    Correct answer: $30$. Student only subtracted $1$; should change tens digit.

18. What is $10$ more than $70$?

    $80$. $70 + 10 = 80$ because the tens digit increases from $7$ to $8$.

19. What is $10$ more than $19$?

    $29$. $19 + 10 = 29$ because the tens digit increases from $1$ to $2$.

20. What is $10$ more than $90$?

    $100$. Adding $10$ to $90$ gives $10$ tens or $100$.

21. Identify the number that is $10$ less than $26$.

    $16$. $26 - 10 = 16$ because the tens digit decreases from $2$ to $1$.

22. What is $10$ less than $90$?

    $80$. Subtract $1$ from tens digit: $9$ becomes $8$.

23. Which option is $10$ more than $63$: $53$, $73$, or $83$?

    $73$. $63 + 10 = 73$ because the tens digit increases from $6$ to $7$.

24. What is $10$ more than $58$?

    $68$. $58 + 10 = 68$ because the tens digit increases from $5$ to $6$.

25. What does adding $10$ to a two-digit number change: the tens digit, the ones digit, or both?

    The tens digit increases by $1$; the ones digit stays the same. Adding $10$ means adding one group of ten.

26. What does it mean to find $10$ more than a two-digit number?

    Add $10$ to the number. Adding $10$ increases the value by one ten.

27. What is $10$ less than $41$?

    $31$. Decrease tens digit from $4$ to $3$.

28. Identify the missing number: $\square - 10 = 33$.

    $43$. To get $33$ after subtracting $10$, start with $43$.

29. What does subtracting $10$ from a two-digit number change: the tens digit, the ones digit, or both?

    The tens digit decreases by $1$; the ones digit stays the same. Subtracting $10$ means removing one group of ten.

30. What does it mean to find $10$ less than a two-digit number?

    Subtract $10$ from the number. Subtracting $10$ decreases the value by one ten.

31. What is $10$ less than $23$?

    $13$. Change the tens digit from $2$ to $1$, keep ones digit $3$.

32. Which digit changes when you subtract $10$ from a two-digit number?

    The tens digit decreases by $1$. Removing $10$ takes away one group of ten from the tens place.

33. What is $10$ less than $99$?

    $89$. $99 - 10 = 89$ because the tens digit decreases from $9$ to $8$.

34. Find and correct the mistake: '$10$ more than $72$ is $73$.' What is correct?

    $10$ more than $72$ is $82$. The tens digit should change from $7$ to $8$, not the ones.

35. What is $10$ less than $40$?

    $30$. $40 - 10 = 30$ because the tens digit decreases from $4$ to $3$.

36. Which option is $10$ less than $63$: $43$, $53$, or $73$?

    $53$. $63 - 10 = 53$ because the tens digit decreases from $6$ to $5$.

37. What is $10$ more than $34$?

    $44$. $34 + 10 = 44$ because the tens digit increases from $3$ to $4$.

38. What is $10$ less than $60$?

    $50$. Change the tens digit from $6$ to $5$, keep ones digit $0$.

39. Identify the number that is $10$ less than $34$.

    $24$. Change the tens digit from $3$ to $2$, keep ones digit $4$.

40. Find and correct the mistake: '$10$ less than $85$ is $75$.' What is correct?

    $10$ less than $85$ is $75$. The statement is already correct; $85 - 10 = 75$.

41. What is $10$ more than $47$?

    $57$. Change the tens digit from $4$ to $5$, keep ones digit $7$.

42. What is $10$ more than $23$?

    $33$. Change the tens digit from $2$ to $3$, keep ones digit $3$.

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