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
- 1.41 − 29 =
- 2.84 − 29 =
- 3.77 − 29 =
- 4.24 − 19 =
- 5.652 + 99 =
- 6.24 + 9 =
- 7.64 + 29 =
- 8.46 − 9 =
- 9.714 + 99 =
- 10.337 + 99 =
- 11.65 − 19 =
- 12.329 + 99 =
- 13.835 − 99 =
- 14.77 + 19 =
- 15.32 + 9 =
- 16.92 − 19 =
- 17.73 + 19 =
- 18.65 + 29 =
- 19.97 − 19 =
- 20.101 − 29 =
- 21.58 + 19 =
- 22.302 + 99 =
- 23.88 − 9 =
- 24.44 − 29 =
- 25.895 − 99 =
- 26.35 + 29 =
- 27.593 + 99 =
- 28.418 − 99 =
- 29.47 + 9 =
- 30.217 − 99 =
- 31.132 + 99 =
- 32.75 + 9 =
- 33.300 − 99 =
- 34.600 + 99 =
- 35.48 + 9 =
- 36.99 − 29 =
- 37.20 − 9 =
- 38.94 − 29 =
- 39.83 − 19 =
- 40.59 + 29 =
Answer key
- 12
- 55
- 48
- 5
- 751
- 33
- 93
- 37
- 813
- 436
- 46
- 428
- 736
- 96
- 41
- 73
- 92
- 94
- 78
- 72
- 77
- 401
- 79
- 15
- 796
- 64
- 692
- 319
- 56
- 118
- 231
- 84
- 201
- 699
- 57
- 70
- 11
- 65
- 64
- 88
Free mental maths lessons, practice and worksheets at talentjr.in/mental-maths