Grade 2 · Set C · Side 1 of 2
Why that step is allowed
C
Start Finish
Goal: 15 min for both sides
Score/ 10
Remember: A step is allowed when the amount stays the same.
1Why can 31 + 19 become 31 + 20 − 1?Moving some from one number to the other keeps the total.Adding the same to both numbers keeps the gap the same.Take a round number, then fix the extra after.
working 2Can 91 − 58 become 40 + 7?AllowedNot allowed
working 3Why can 41 + 38 become 41 + 40 − 2?Moving some from one number to the other keeps the total.Take a round number, then fix the extra after.Adding the same to both numbers keeps the gap the same.
working 436 + 48 = 70 + 14. Can 70 + 14 become 80 + 4?AllowedNot allowed
working 5Why can 12 + 28 become 12 + 30 − 2?Take a round number, then fix the extra after.Moving some from one number to the other keeps the total.Adding the same to both numbers keeps the gap the same.
working
Grade 2 · Set C · Side 2 of 2
Why that step is allowed
C
Start Finish
Goal: 15 min for both sides
Score/ 10
6Can 31 + 26 become 3 + 1 + 2 + 6?AllowedNot allowed
working 7Can 93 − 68 become 95 − 70?AllowedNot allowed
working 8Can 55 − 16 become 51 − 20?AllowedNot allowed
working 9Can 81 − 52 become 30 + 1?AllowedNot allowed
working 10Can 37 + 59 become 37 + 60 − 1?AllowedNot allowed
working Answer key · Grade 2 · Set C
Why that step is allowed
1Take a round number, then fix the extra after.
2Not allowed
3Take a round number, then fix the extra after.
4Allowed
5Take a round number, then fix the extra after.
6Not allowed
7Allowed
8Not allowed
9Not allowed
10Allowed
Mark each answer, count the right ones and write the score on the sheet. Beat your own time next time.