For 25.01.2013

Break Up and Bridge (Review)

This strategy is similar to front-end addition except that you begin with all of the first number and then add on parts of the second number beginning with the largest place value.  

Examples

a) For 45 + 36, think, “45 and 30 (from the 36) is 75, and 75 plus 6 (the

rest of the 36) is 81.”

b) For 537 + 208, think, “537 and 200 is 737, and 737 plus 8 is 745.”

c) For 5300 plus 2400, think, “5300 and 2000 (from the 2400) is 7300

and 7300 plus 400 (from the rest of 2400) is 7700.”

d) For 3.6 plus 5.3, think, “3.6 and 5 (from the 5.3) is 8.6 and 8.6 plus

0.3 (the rest of 5.3) is 8.9.”

Practice Items

37 + 42 =                   72 + 21 =                          88 + 16 =

74 + 42 =                   325 + 220 =                     301 + 435 =

747 + 150 =               142 + 202 =                     370 + 327 =

7700 + 1200 =           4100 + 3600 =                 5700 + 2200 =

7300 + 1400 =           2800 + 6100 =                 3300 + 3400 =

4.2 + 3.5 =                 6.3 + 1.6 =                       4.2 + 3.7 =

6.1 + 2.8 =                 0.32 + 0.56 =                   2.08 + 3.2 =

4.15 + 3.22 =             5.43 + 2.26 =                   6.03 + 2.45 =

15.45 + 1.25 =           43.30 + 7.49 =                 70.32 + 9.12 =