Math A.Tube.com
....................................................................................................................................................................
Trade-First Method
Trade First
Closest to the traditional standard is a method that Everyday Mathematics calls
"trade first". It is the Everyday Math focus algorithm for subtraction. It is a two
stage process, first working right to left to do all the borrowing (recording the
intermediate results above the top number) and then a second pass, in any
order, doing the subtractions. The intermediate results are two-digit numbers,
so one needs to use wide columns, and it is recommended to separate the
columns with clear vertical lines. In the example at right, 325 - 58, we first
recognize that the ones column needs borrowing, so we replace 2*10+5 by
1*10+15. Then we recognize that the tens column also needs borrowing, so we
replace 3*100+1*10 by 2*100+11*10. Then we do the subtraction in each
column.
Home
Together, we'll learn
Math Glossary
Homepage
The glossary anyone can edit