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
- 1.291 − 99 =
- 2.72 − 9 =
- 3.58 − 9 =
- 4.294 + 99 =
- 5.30 − 9 =
- 6.40 − 29 =
- 7.58 + 29 =
- 8.79 − 19 =
- 9.60 + 29 =
- 10.38 + 19 =
- 11.48 + 9 =
- 12.15 − 9 =
- 13.51 − 29 =
- 14.847 − 99 =
- 15.42 + 9 =
- 16.69 + 9 =
- 17.87 − 9 =
- 18.31 + 9 =
- 19.25 − 9 =
- 20.22 + 19 =
- 21.43 − 9 =
- 22.43 + 29 =
- 23.100 − 29 =
- 24.28 + 9 =
- 25.17 + 19 =
- 26.44 + 19 =
- 27.55 − 19 =
- 28.277 + 99 =
- 29.34 − 19 =
- 30.480 + 99 =
- 31.70 − 29 =
- 32.425 + 99 =
- 33.52 − 29 =
- 34.416 − 99 =
- 35.29 + 19 =
- 36.503 + 99 =
- 37.152 + 99 =
- 38.25 − 19 =
- 39.81 − 9 =
- 40.78 − 9 =
Answer key
- 192
- 63
- 49
- 393
- 21
- 11
- 87
- 60
- 89
- 57
- 57
- 6
- 22
- 748
- 51
- 78
- 78
- 40
- 16
- 41
- 34
- 72
- 71
- 37
- 36
- 63
- 36
- 376
- 15
- 579
- 41
- 524
- 23
- 317
- 48
- 602
- 251
- 6
- 72
- 69
Free mental maths lessons, practice and worksheets at talentjr.in/mental-maths