[image]

The advantage of this method, for students who
have difficulty with the traditional algorithm, is that mental regrouping is not required; all the partial
sums are recorded separately before being combined.

Also, the method
yields a correct sum whether the partial sums begin
with the ones or the left-most column.
Left-to-right addition (see figs. 1b and

[image]

In figure 4, instead of a ten being taken from the
6 tens, as would be done in the traditional algorithm,
a ten is added to the 5 ones to give 15 ones.
To compensate, 1 ten is added to the subtrahend,
resulting in 8 tens. The 9 ones are then subtracted
from the 15 ones. The next step is to add 10 tens to
the 6 tens in the minuend so that 8 tens can be subtracted.
To compensate, 1 hundred is added to the 8 hundreds, yielding 9 hundreds. The amount of
8 tens is then subtracted from 16 tens. Next, 10 hundredsadded to the 4 hundreds results in 14 hundreds;
to compensate, 1 thousand is added to the
subtrahend. Then 9 hundreds can be subtracted
from 14 hundreds, and 2 thousand is subtracted
from 5 thousand.

[image]

Low-stress subtraction involves renaming the
minuend and writing it between the original minuend
and the subtrahend before subtracting individual
digits (Hutchings 1975). In figure 5, 6 tens are
renamed as 5 tens and 10 ones; the 10 ones are regrouped with the 5 ones to make 15 ones. Next,
because 7 tens cannot be subtracted from 5 tens,
4 hundreds is renamed as 3 hundreds and 10 tens;
the 10 tens are regrouped with the 5 tens to make
15 tens. This process continues until the minuend
is rewritten so that no impasses to subtraction
remain and the problem is ready to be completed.

• Based on place value

EXAMPLE: 456 + 20 =
(400 + 50 +20 +6)
470 + 6

476

• Count bys

455 + 10 + 10

455 + 10 = 465

465 + 10 = 475

475 + 1 = 476

• Count on

237 + 43

237 + 10 + 10 + 10 + 10 + 1 + 1 +1

247, 257, 267, 277, 278, 279, 280