2148 ARITHMETIC
Method of work.
From 457 take 268. 457 268
Write the subtrahend under the minuend.
189 Begin with the units to subtract.
We cannot take 8 units from' 7 units, so we take 1 ten from the 5 tens (leaving 4 tens) and add it to the 7 units, making 17 units. We can now take 8 units from 17 units, leaving 9 units.
In like manner we cannot take 6 tens from 4 tens, so we take 1 hundred from the 4 hundreds (leaving 3 hundreds) and add it to the 4 tens, making 14 tens.
We can now take 6 tens from 14 tens, leaving 8 tens. 2 hundreds from 3 hundreds leaves 1 hundred. Thus the difference is 189.
In doing the example the pupil thinks:—8 from 17 leaves 9; 6 from 14 leaves 8; 2 from 3 leaves 1.
Proof.—Add the remainder to the subtrahend. The sum should equal the minuend.
THE AUSTKIAN METHOD.
The Austrian method of subtraction emphasizes not so much what remains after taking the subtrahend from the minuend, as what must be added to the subtrahend to make the minuend.
This is also called the "shop" method, as it is generally employed in making change. Much practice along this line is recommended.
From 697 subtract 284.
697 By the Austrian method we say 4 units and 3 units=7 units.
284 Write 3 in the units' place. 8 tens and 1 tem=9 tens. Write 1 in
tens7 place. 2 hundreds and 4 hundreds=6 hundreds. Write 4 in
413 hundreds' place, and the result is 413.
From 457 take 268.
457 The pupil should be guided to say 8 units and 9 units=17
268 units. Put down 9. 6 tens and 1 ten are 7 tens and 8 tens=15
tens. Put down 8. 2 hundreds and 1 hundred are 3 hundreds
189 and 1 hundred=4 hundreds. Put down 1, and the result is 189.
Add ten to each minuend digit that is smaller than the corresponding subtrahend digit, and make up for that by adding one to the next higher subtrahend digit.
