Express a fraction with denominator 10 as an equivalent fraction with denominator 100 and use this to add fractions with denominators 10 and 100 (e.g. 3/10 + 4/100 = 34/100)
You already know that a tenth is 1 out of 10 equal parts, like 3/10. A hundredth is 1 out of 100 equal parts. Cut each tenth into 10 smaller pieces and you get 100 pieces in all. So every tenth is worth ten hundredths: multiply the top number and the bottom number by 10.
Zara has 3/10 of a pizza, and her friend gives her 4/100 more. First she changes 3/10 into hundredths: 3/10 = 30/100. Then she adds: 30/100 + 4/100 = 34/100. Zara now has 34/100 of the pizza.
Why can you add the top numbers like that? Because 30/100 and 4/100 are both counting the same size of piece: little hundredths. 30 of them and 4 more of them make 34 of them, so the answer is 34/100. The bottom number stays 100, since the pieces did not change size. If the bottom numbers do not match yet, change the tenths into hundredths first.
Every tenth equals ten hundredths, so turn tenths into hundredths first, then add the top numbers together.
The rewritten reading was written for this dataset. Practice items adapted from WeBWorK Open Problem Library problems by Carl Yao (PCC) (CC BY-NC-SA 3.0).
Last summer at Meadow Lane you learned to give a fraction a new name: multiply the top and the bottom by the same number and the amount stays put. This morning Leo pegs string across the strawberry bed, ten rows one way and ten rows the other way, so the bed is cut into 100 little seed squares.
One row of the bed is 1/10 of it. How many seed squares is one row?
Jobs that lean on this skill. Follow one to see everything it is built on.
17 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.