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
- 1.73 − 9 =
- 2.27 + 19 =
- 3.15 + 29 =
- 4.749 + 99 =
- 5.71 + 29 =
- 6.18 + 19 =
- 7.33 − 19 =
- 8.34 − 9 =
- 9.23 − 9 =
- 10.695 − 99 =
- 11.419 − 99 =
- 12.69 − 9 =
- 13.47 − 9 =
- 14.900 − 99 =
- 15.53 − 9 =
- 16.45 − 29 =
- 17.614 − 99 =
- 18.25 + 9 =
- 19.32 − 19 =
- 20.20 + 29 =
- 21.75 − 9 =
- 22.107 + 99 =
- 23.64 + 9 =
- 24.104 − 29 =
- 25.38 + 9 =
- 26.30 − 9 =
- 27.66 − 29 =
- 28.334 + 99 =
- 29.35 − 19 =
- 30.199 − 99 =
- 31.25 + 29 =
- 32.82 − 9 =
- 33.60 + 19 =
- 34.522 + 99 =
- 35.40 − 19 =
- 36.175 + 99 =
- 37.70 − 29 =
- 38.33 + 19 =
- 39.75 + 19 =
- 40.30 − 19 =
Answer key
- 64
- 46
- 44
- 848
- 100
- 37
- 14
- 25
- 14
- 596
- 320
- 60
- 38
- 801
- 44
- 16
- 515
- 34
- 13
- 49
- 66
- 206
- 73
- 75
- 47
- 21
- 37
- 433
- 16
- 100
- 54
- 73
- 79
- 621
- 21
- 274
- 41
- 52
- 94
- 11
Free mental maths lessons, practice and worksheets at talentjr.in/mental-maths