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
- 1.47 + 9 =
- 2.64 + 29 =
- 3.20 + 19 =
- 4.66 − 9 =
- 5.71 + 9 =
- 6.18 + 29 =
- 7.65 − 19 =
- 8.90 − 19 =
- 9.45 + 29 =
- 10.51 − 29 =
- 11.71 + 19 =
- 12.49 + 9 =
- 13.14 + 9 =
- 14.23 + 19 =
- 15.99 − 29 =
- 16.43 + 19 =
- 17.34 + 19 =
- 18.78 − 29 =
- 19.69 − 29 =
- 20.74 + 19 =
- 21.56 − 29 =
- 22.492 − 99 =
- 23.317 + 99 =
- 24.32 + 9 =
- 25.52 − 29 =
- 26.200 − 99 =
- 27.49 − 9 =
- 28.63 + 29 =
- 29.127 + 99 =
- 30.14 − 9 =
- 31.43 − 19 =
- 32.46 + 19 =
- 33.61 + 9 =
- 34.62 − 19 =
- 35.69 + 29 =
- 36.83 − 29 =
- 37.59 + 19 =
- 38.17 − 9 =
- 39.41 − 29 =
- 40.31 + 29 =
Answer key
- 56
- 93
- 39
- 57
- 80
- 47
- 46
- 71
- 74
- 22
- 90
- 58
- 23
- 42
- 70
- 62
- 53
- 49
- 40
- 93
- 27
- 393
- 416
- 41
- 23
- 101
- 40
- 92
- 226
- 5
- 24
- 65
- 70
- 43
- 98
- 54
- 78
- 8
- 12
- 60
Free mental maths lessons, practice and worksheets at talentjr.in/mental-maths