Equal Addition.

TEACHING ADDITION, SUBTRACTION, AND PLACE VALUE, BOOK 5, PAGE 38

EQUAL ADDITION

WALT: I am learning to solve subtraction problems by equal additions that turn one of the numbers into a tidy number.

Activities 1 - 4

WALT: Solve subtraction problems by equal additions that turn one of the numbers into a tidy number.

Prior Knowledge Required: To do this I need to be confident adding to a number to change it into a tidy number.

1)

Question	Answer	Question	Answer
A. 348 + = 350	348 + 2 = 350	F. 96 +  = 100	96 + 4 = 100
B. 212 -  = 210	212 - 2 = 210	G. 142 -  = 140	142 - 2 = 140
C. 456 +  = 460	456 + 4 = 460	H. 117 +  = 120	117 + 3 = 120
D. 711 -  = 710	711 - 1 = 710	I. 196 +  = 200	196 + 4 = 200
E. 314 -  = 310	314 - 4 = 310	J. 214 -  = 210	214 - 4 = 210

New Strategy with Materials: Remember subtraction is all about finding the difference between two numbers or subtract the same amount from both numbers the difference will remain the same.

2) You may use a number line or empty number line to answer these questions. For question a) I added 4 to 596 to make 600 which is a tidy number. Since I added 4 to 596 I also had to add 4 to 661.

Question	Change it to a tidy number	Answer
A. 661 - 596 =	665 - 600 =	65
B. 467 - 399 =	468 - 400 =	68
C. 543 - 397 =	547 - 400 =	147
D. 552 - 496 =	556 - 500 =	56
E. 234 - 96 =	238 - 100 =	138
F. 467 - 295 =	472 - 300 =	172
G. 900 - 198 =	902 - 200 =	702

3) Do not use a number line to answer these questions.

Question	Change it to a tidy number	Answer
A. 601 - 299 =	602 - 300 =	302
B. 750 - 96 =	754 - 100 =	654
C. 805 - 96 =	809 - 100 =	709
D. 506 - 196 =	510 - 200 =	310
E. 765 - 290 =	765 - 290 =	475