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
- 1.89 − 19 =
- 2.20 − 9 =
- 3.94 − 19 =
- 4.41 + 19 =
- 5.41 + 9 =
- 6.77 + 19 =
- 7.51 + 9 =
- 8.37 + 9 =
- 9.57 − 9 =
- 10.46 + 9 =
- 11.43 + 19 =
- 12.43 − 19 =
- 13.633 + 99 =
- 14.29 − 19 =
- 15.24 + 19 =
- 16.725 + 99 =
- 17.106 − 29 =
- 18.35 + 29 =
- 19.73 − 19 =
- 20.300 − 99 =
- 21.78 + 29 =
- 22.43 + 29 =
- 23.331 + 99 =
- 24.35 − 19 =
- 25.69 + 9 =
- 26.40 + 19 =
- 27.41 + 29 =
- 28.36 − 9 =
- 29.55 − 9 =
- 30.22 + 19 =
- 31.22 + 9 =
- 32.47 + 19 =
- 33.28 + 9 =
- 34.92 − 29 =
- 35.71 − 19 =
- 36.55 + 19 =
- 37.32 − 9 =
- 38.714 − 99 =
- 39.755 − 99 =
- 40.33 + 29 =
Answer key
- 70
- 11
- 75
- 60
- 50
- 96
- 60
- 46
- 48
- 55
- 62
- 24
- 732
- 10
- 43
- 824
- 77
- 64
- 54
- 201
- 107
- 72
- 430
- 16
- 78
- 59
- 70
- 27
- 46
- 41
- 31
- 66
- 37
- 63
- 52
- 74
- 23
- 615
- 656
- 62
Free mental maths lessons, practice and worksheets at talentjr.in/mental-maths