Mental Math Grade 6 Teacher's Guide

4) For 6.45 – 1.98, think, “Add 2 hundredths to both numbers to get 6.47
– 2.00, so 4.47 is the answer.”
For 5.67 – 2.03, think, “Subtract 3 hundredths from both numbers to
get 5.64 – 2.00. The answer is 3.64.”
Practice Items
85 – 18 = 42 - 17 = 36 – 19 =
78 – 19 = 67 -18 = 75 – 38 =
649 - 299 = 563 – 397 = 823 – 298 =
912 – 797 = 737 - 398 = 456 – 198=
948 – 301 = 437 – 103 = 819 – 504 =
6.4 – 3.9 = 7.6 – 4.2 = 8.7 – 5.8 =
4.3 – 1.2 = 9.1 – 6.7 = 5.0 – 3.8 =
6.3 – 2.2 = 4.7 – 1.9 = 12.5 – 4.3 =
15.3 – 5.7 = 8.36 – 2.99 = 7.45 – 1.98 =
Add your own practice items
• Break Up and Bridge (Review)
With this subtraction strategy, you start with the larger number (the
minuend) and subtract the highest place value of the second number first
(the subtrahend), and then the rest of the subtrahend.
Examples
a) For 92 – 26, think, “92 subtract 20 (from the 26) is 72 and 72 subtract
6 is 66.”
b) For 745 – 203, think, “745 subtract 200 (from the 203) is 545 and 545
minus 3 is 542.”
c) For 8369 - 204, think, “8369 subtract 200 is 8169 and minus 4 (the
rest of the 204) is 8165 .
Practice Items
79 – 37 = 93 – 72 = 98 – 22 =
79 – 41= 74 – 15 = 77 – 15 =
36 Mental Math – Grade 6