Tell what happens to the tens digit and ones digit when you add tens.

Question

The question is exactly what's listed above. i don't understand how to help my child. Tell what happens to the tens digit and ones digit when you add tens.

Answer 1

First, explain that the Decimal Number System is a positional number system.  That means:

  1.  each position represents a power of the number base (in this case, 10 ).  So, there is ones place (1=10⁰), tens place (10=10¹), hundreds place (100=10²), etc.  Also, on the other side of the decimal point, there is tenths place (1/10 = 10^-1), hundredths place (1/100 = 10^-2), etc.

  2.  a Zero (that is, 0) fills the place when no value is associated with that position.  Thus, 101 means 1 hundred and 1 one (no tens).

 

So, if you have a number and add 10, the zero is added to the value that the number has in its ones place, there is no carry, and the 1 is added to the value it has in its tens place.  Now, if this produces a sum that is greater than 9 (the largest single digit), then the ones place of the sum is put in the tens place of the answer and the tens place of the sum is carried to add to the hundreds place of the original number.  For example:

    1 9 2

+    1 0

  --------

    2 0 2               [2 in ones place does not change;

                           9+1 = 10, so 0 goes in tens place and 1 is carried to hundreds place;

                              that 1 is added to the 1 in hundreds place to produce 2 hundred.]

Answer 2

This is my guess as to what they are asking:

 

The ones digit remains the same when you add ten.

The tens digit increases by 1 every time you add ten.