10

LESSON

Solving Digit

Problems

The symbols 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9 are calleddigits. They are used to

make our numbers. A number such as 28 is called a two-digit number. The

eight is the one’s digit and the two is the ten’s digit. The one’s digit is also

called the unit’s digit. The number 28 means the sum of 2 tens and 8 ones and

can be written 2 10 þ 8 ¼ 20 þ8 or 28. The number 537 is called a three-

digit number. The seven is the one’s digit, the three is the ten’s digit, and the

five is the hundred’s digit. It can be written as 5 100 þ 3  10 þ7or

500 þ 30 þ 7 ¼537.

A digit problem will sometimes ask you to find the sum of the digits. In

order to do this, just add the digits. For example, the sum of the digits of the

number 537 is 5þ 3 þ 7 ¼15.

Sometimes digit problems will ask you to reverse the digits. If the digits of

the number 36 (3 10 þ6) are reversed, the new number is 63 (6 10 þ3).

Using this information and the material in the previous lesson, you will be

able to solve digit problems.

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