The Psychology of ArithmeticThorndike, Edward L. (Edward Lee)
Science
The Psychology of Arithmetic
Thorndike, Edward L. (Edward Lee)
Arithmetic -- Study and teaching
Therefore the quotient of 1825 divided by 4 is 456-1/4, or 456 and
1 remainder.
SHORT DIVISION: INDUCTIVE EXPLANATION
Dividing Large Numbers
1. Tom, Dick, Will, and Fred put in 2 cents each to buy an eight-cent
bag of marbles. There are 128 marbles in it. How many should each boy
have, if they divide the marbles equally among the four boys?
-----
4 |128
_Think "12 = three 4s." Write the 3 over the 2 in the tens column._
_Think "8 = two 4s." Write the 2 over the 8 in the ones column._
_32 is right, because 4 × 32 = 128._
2. Mary, Nell, and Alice are going to buy a book as a present for
their Sunday-school teacher. The present costs 69 cents. How much
should each girl pay, if they divide the cost equally among the
three girls?
----
3|69
_Think "6 = .... 3s." Write the 2 over the 6 in the tens column._
_Think "9 = .... 3s." Write the 3 over the 9 in the ones column._
_23 is right, for 3 × 23 = 69._
3. Divide the cost of a 96-cent present equally among three girls. How
much should each girl pay?
------
3|96
4. Divide the cost of an 84-cent present equally among 4 girls. How
much should each girl pay?
5. Learn this: (Read ÷ as "_divided by_.")
12 + 4 = 16. 16 is the sum.
12 - 4 = 8. 8 is the difference or remainder.
12 × 4 = 48. 48 is the product.
12 ÷ 4 = 3. 3 is the quotient.
6. Find the quotients. Check your answers by multiplying.
---- ---- ---- ----- ----- -----
3|99 2|86 5|155 6|246 4|168 3|219
[Uneven division is taught by the same general plan, extended.]
LONG DIVISION: DEDUCTIVE EXPLANATION
To Divide by Long Division
1. Let it be required to divide 34531 by 15.
_Operation_
Divided
Divisor 15)34531(2302-1/15 Quotient
30
--
45
45
--
31
30
--
1 Remainder
For convenience we write the divisor at the left and the quotient at the
right of the dividend, and begin to divide as in Short Division.
15 is contained in 3 ten-thousands 0 ten-thousands times; therefore,
there will be 0 ten-thousands in the quotient. Take 34 thousands; 15 is
contained in 34 thousands 2 thousands times; we write the 2 thousands in
the quotient. 15 × 2 thousands = 30 thousands, which, subtracted from 34
thousands, leaves 4 thousands = 40 hundreds. Adding the 5 hundreds, we
have 45 hundreds.
15 in 45 hundreds 3 hundreds times; we write the 3 hundreds in the
quotient. 15 × 3 hundreds = 45 hundreds, which subtracted from 45
hundreds, leaves nothing. Adding the 3 tens, we have 3 tens.
15 in 3 tens 0 tens times; we write 0 tens in the quotient. Adding to
the three tens, which equal 30 units, the 1 unit, we have 31 units.
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