Adding 9, 19 and 99 Mental Maths Worksheet
How to do it in your head (Round and adjust): Add 9, 19, 99: add 10, 20, 100, then take 1 away. Take away 9, 19, 99: take away 10, 20, 100, then add 1 back. Ask yourself: did I use too much or too little?
NameDateTime takenScore ___ / 40
- 1.32 + 9 =
- 2.45 − 19 =
- 3.55 + 9 =
- 4.60 + 29 =
- 5.53 + 9 =
- 6.77 − 9 =
- 7.88 − 9 =
- 8.80 − 29 =
- 9.23 + 9 =
- 10.49 + 9 =
- 11.50 − 9 =
- 12.72 − 19 =
- 13.83 − 9 =
- 14.54 + 29 =
- 15.35 + 9 =
- 16.58 + 9 =
- 17.63 − 19 =
- 18.269 + 99 =
- 19.25 − 9 =
- 20.67 − 9 =
- 21.43 − 19 =
- 22.19 + 9 =
- 23.501 + 99 =
- 24.18 − 9 =
- 25.52 − 19 =
- 26.78 + 9 =
- 27.53 + 19 =
- 28.54 − 19 =
- 29.14 + 29 =
- 30.42 − 9 =
- 31.206 − 99 =
- 32.40 + 9 =
- 33.330 − 99 =
- 34.28 − 19 =
- 35.631 − 99 =
- 36.54 + 19 =
- 37.60 + 19 =
- 38.298 + 99 =
- 39.24 + 19 =
- 40.43 + 9 =
Answer key
- 41
- 26
- 64
- 89
- 62
- 68
- 79
- 51
- 32
- 58
- 41
- 53
- 74
- 83
- 44
- 67
- 44
- 368
- 16
- 58
- 24
- 28
- 600
- 9
- 33
- 87
- 72
- 35
- 43
- 33
- 107
- 49
- 231
- 9
- 532
- 73
- 79
- 397
- 43
- 52
Free mental maths lessons, practice and worksheets at talentjr.in/mental-maths