5. Express a fraction with denominator 10 as an equivalent fraction with denominator 100, and use this technique to add two fractions with respective denominators 10 and 100. [Students who can generate equivalent fractions can develop strategies for adding fractions with unlike denominators in general. But addition and subtraction with unlike denominators in general is not a requirement at this grade.] For example, express 3/10 as 30/100, and add 3/10 + 4/100 = 34/100.
– Khan Academy (iOS – free – iPhone/iPad)