A part of a number and the number from its part
Find a part of a number and find the number from its part: first one part, then the whole or several parts. Section: Grade 3 (part of a number and the number from its part); Grade 5-6 fractions are in another studio.
- Ukraine: grade 3
- Russia: grade 5
Guide
A studio for Ukrainian grade 3 (НУШ textbooks, part 1, parts of a number). Two opposite questions. Find a part of a number: a quarter of 20 is 20 : 4 = 5. Find the number from its part: if a quarter of the number is 5, the whole is 5 · 4 = 20.
The book draws a bar split into equal parts. If the whole is known, divide it by the number of parts. If a part is known, multiply by the number of parts. For several parts (three fifths) find one part first and then take the needed number of them.
In each task build the diagram: put a number into the whole or into a part, and put ? where the unknown is. The «why?» question asks which operation answers which question.
Fractions are written with a fraction bar here, and in the problems with words: a quarter, a third, a fifth.