Chapter 2: Arithmetic 29you already had. You’ve got 18 ones. Deal them out into the 9 piles, and each pile will get 2 ones.
Each pile got 8 tens and 2 ones. That’s 82. 738 z 9 = 82.
No one wants to think about all that dealing out and exchanging every time there’s a problem
to be done, especially if the numbers are large. That’s why there’s an algorithm. Let’s look at the
same problem with the algorithm. We set up the division problem with the divisor outside and
the dividend, the number that’s being divided up, inside the long division symbol, or division
bracket. As you complete the problem, the quotient will be written on top of the bracket.
9 738
Take the process digit by digit. How many 9s are there in 7? None, so you can put a zero over
the top of the 7. Multiply the digit you just put in the quotient, 0, times the divisor, 9, and put
the result under the 7. Subtract, and check that the result of the subtraction is smaller than the
divisor. 7 is less than 9, so move on.
Those 7 hundreds change to 70 tens and get added to the 3 tens to make 73 tens. Show that by
bringing the 3 down. Divide 9 into 73. It goes 8 times, so put an 8 up in the quotient. Multiply
that 8 times the divisor, put the product (72) under the 73, and subtract. Check that the result is
less than the divisor.
That’s the one leftover ten, which changes to 10 ones. Bring down the 8 to make 18 ones and
divide 9 into 18. Put the 2 in the quotient, multiply 2 times the divisor, put the 18 under the 18
and subtract.
9 738
0
709 738
0
73
720819 738
0
73
72008218
18