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
- 1.282 + 99 =
- 2.47 − 9 =
- 3.71 − 9 =
- 4.80 + 9 =
- 5.211 − 99 =
- 6.55 + 19 =
- 7.89 − 9 =
- 8.49 + 29 =
- 9.193 − 99 =
- 10.27 + 9 =
- 11.39 − 9 =
- 12.25 − 19 =
- 13.252 + 99 =
- 14.22 + 9 =
- 15.50 − 29 =
- 16.64 + 29 =
- 17.56 − 9 =
- 18.313 + 99 =
- 19.25 + 19 =
- 20.175 − 99 =
- 21.147 + 99 =
- 22.67 + 19 =
- 23.57 + 29 =
- 24.86 − 9 =
- 25.38 − 9 =
- 26.77 + 9 =
- 27.502 − 99 =
- 28.74 − 29 =
- 29.63 + 19 =
- 30.58 + 9 =
- 31.401 + 99 =
- 32.12 + 9 =
- 33.17 + 9 =
- 34.79 − 29 =
- 35.30 − 9 =
- 36.92 − 29 =
- 37.81 − 9 =
- 38.53 − 9 =
- 39.73 − 29 =
- 40.33 − 29 =
Answer key
- 381
- 38
- 62
- 89
- 112
- 74
- 80
- 78
- 94
- 36
- 30
- 6
- 351
- 31
- 21
- 93
- 47
- 412
- 44
- 76
- 246
- 86
- 86
- 77
- 29
- 86
- 403
- 45
- 82
- 67
- 500
- 21
- 26
- 50
- 21
- 63
- 72
- 44
- 44
- 4
Free mental maths lessons, practice and worksheets at talentjr.in/mental-maths