Project Math Access DVD 02 - Abacus- Part 02
Transcript Start

Audio Description: Part two; abacus logic method; subtraction.

PETER: The next one is a subtraction problem. and it's 167 - 86. So you will set 167 all the way to the right. On the abacus, to the extreme right... 167. And you want to subtract 86. So... l will... first go to the tens place... column and we can't subtract 80 directly so we'll have to go to the left and subtract 100.

TEACHER: To make it simpler, say "Can I take 10 away"?

PETER: Yeah, can ltake 10 away, and I can...

TEACHER: in the column directly to the left.

PETER: So I'll take it away and that is 2 too many. so I'll add 2 

TEACHER: To the 10's column

PETER: To the 10's column, and now my abacus reads 87. And I want to subtract 6 from the 1's column which I can do directly.

PETER: So now the final answer is 81.

TEACHER: Okay.