Add and Subtract Tenths and Hundredths

Adding 10ths and 100ths

By Sarah Auchter

Multiple Choice

When you add or subtract fractions, what does the denominator do?

• Add the denominators

• Subtract the denominators

• Delete the denominators

• It stays the same.

Why don't we add or subtract the denominators?

​

Right, it stays the same.

Multiple Choice

$$\frac{2}{4}+\frac{1}{4}=$$  

• $$\frac{3}{8}$$  

• $$\frac{3}{4}$$  

• $$\frac{1}{4}$$  

Multiple Choice

$$\frac{7}{8}-\frac{2}{8}=$$  

• $$\frac{4}{8}$$  

• $$\frac{9}{8}$$  

• $$\frac{5}{8}$$  

• $$\frac{5}{0}$$  

​If the denominator has to stay the same, how is this problem possible??

So, how would we do this??

I need to change one or both of the fractions into equivalent fractions with the same denominator.

Right, you have to make a change.

0​

​?

Remember, tenths are like dimes, and hundredths are like pennies.

So, 7 tenths are like 7 dimes. How much money is seven dimes?

Multiple Choice

7 dimes equals how much money?

• seven cents

• seventy cents

• seven dollars

• seventy dollars

Multiple Choice

If seven dimes equals seventy cents, then which of these are true?

• $$\frac{7}{10}=\frac{7}{100}$$  

• $$\frac{7}{10}=\frac{70}{100}$$  

What is the total now?

Now the problem is this:

Multiple Choice

$$\frac{70}{100}+\frac{9}{100}=$$  

• $$\frac{16}{100}$$  

•   $$\frac{79}{10}$$  

• $$\frac{79}{100}$$  

Find the pattern:

​tenths (10th)	​hundredths (100th)
​4	​40
​5	​50
​6	​60
​8	​??

Multiple Choice

8 tenths would equal:

• 80 hundredths

• 8 hundredths

• 8 ones

• 80 ones

Find the pattern:

​tenths (10th)	​hundredths (100th)
​4	​40
​5	​50
​6	​60
​8	​80

Adding or subtracting 10ths and 100ths means:

Change the 10ths into hundredths.

Do this by putting a zero after the numerator and denominator.

Then add or subtract the fraction.​

Multiple Choice

$$\frac{6}{10}+\frac{30}{100}=$$  

• $$\frac{60}{100}+\frac{30}{100}=\frac{90}{100}$$  

• $$\frac{6}{100}+\frac{30}{100}=\frac{36}{100}$$  

Multiple Choice

$$\frac{37}{100}-\frac{3}{10}=$$  

• $$\frac{37}{100}-\frac{30}{100}=\frac{7}{100}$$  

• $$\frac{37}{100}-\frac{3}{100}=\frac{34}{100}$$  

Multiple Choice

$$\frac{59}{100}+\frac{2}{10}=$$  

• $$\frac{59}{100}+\frac{20}{100}=\frac{79}{100}$$  

• $$\frac{59}{100}+\frac{2}{100}=\frac{61}{100}$$  

Multiple Choice

$$\frac{8}{10}-\frac{12}{100}=$$  

• $$\frac{80}{100}-\frac{12}{100}=\frac{68}{100}$$  

• $$\frac{8}{100}-\frac{12}{100}=\frac{4}{100}$$  

Multiple Choice

Think!!!

$$\frac{12}{10}+\frac{3}{100}=$$  

• $$\frac{12}{100}+\frac{3}{100}=\frac{15}{100}$$  

• $$\frac{120}{100}+\frac{3}{100}=\frac{123}{100}\ or\ \ 1\frac{23}{100}$$  

Multiple Choice

$$\frac{9}{10}-\frac{4}{100}=$$  

• $$\frac{9}{100}-\frac{40}{100}=\frac{31}{100}$$  

• $$\frac{90}{100}-\frac{4}{100}=\frac{86}{100}$$  

• $$\frac{9}{100}-\frac{4}{100}=\frac{5}{100}$$