Math Concepts: Number Words and Rounding

Study Notes

Number Words and Values

Numbers 21 to 29 are expressed as "two tens plus one", "two tens plus two", etc.
30 is "three tens"
40 is "four tens"
50 is "five tens"
60 is "six tens"
70 is "seven tens"
80 is "eight tens"
90 is "nine tens"
100 is "one hundred"

Rounding to the Nearest Ten

To round a number to the nearest ten, look at the ones digit.
If the ones digit is 5 or greater, round up to the next ten.
If the ones digit is 4 or less, round down to the previous ten.
Example: 30 rounds to 30
Example: 31 rounds to 30
Example: 35 rounds to 40
Example: 51 rounds to 50
Example: 55 rounds to 60
Example: 72 rounds to 70
Example: 78 rounds to 80
Example: 83 rounds to 80
Example: 94 rounds to 90
Example: 98 rounds to 100
Example: 19 rounds to 20
Example: 26 rounds to 30
Example: 87 rounds to 90

Place Value

Example: In number 47, the place value of 7 is units or ones and the place value of 4 is tens
Example: In number 85, the place value of 5 is units or ones and the place value of 8 is tens

Description

This quiz covers important math concepts related to number words and values, rounding to the nearest ten, and understanding place value. Test your knowledge on expressing numbers, determining rounding rules, and identifying place values in different numbers.