For subtraction, add complement of tens in 1's column, take away 1 in 10's column
10 - 7 (10 take away 7)
Complement of 7 is 3, add 3 in 1's column, subtract 1 in 10's column
Answer is 3
10 - 6 (10 minus 6)
Complement of 6 is 4, add 4 in 1's column, take away 1 in 10's column
Answer is 4
11 - 8 (11 take away 8)
Complement of 8 is 2, add 2 in 1's column, take away 1 in 10's column
Answer is 3
12 - 9 (12 take away 9)
Complement of 8 is 3, add 3 in 1's column, take away 1 in 10's column
Answer is 3
17 - 9 (17 take away 9)
Complement of 9 is 1, add 1 in 1's column, take away 1 in 10's column
Answer is 8
12 - 8 (12 take away 8)
Complement of 8 is 2, add 2 in 1's column, take away 1 in 10's column
Answer is 4
Now try doing Worksheet 25
Video: Abacus Lesson 25: Subtraction, complements of 10, 1's column
Acknowledgement: Above is a summary of the HEV Project: Video, Abacus Lesson 25: Subtraction, complements of 10, 1's column
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