Idea 18of 23Builds onThe hundredths digit is a shortcut
Rounding up into the next whole
What happens when 2.96 rounds up past 2.9?
Today you'll discover
- what one tenth more than 2.9 is
- why it is not 2.10
- why the zero in 3.0 stays
Think first2.96, near the end of the 2s
2.96 is closer to the next tenth up from 2.9. How is that tenth written?
Decide first, then press Next. Read the label at the right end of the line.
A number line from 2.9 to 3.0 with a dot at 2.96. Brackets read 6 hundredths back to 2.9 and 4 hundredths on to 3.0. Then 3.0 is ringed: 2.96 rounds to 3.0, and a blue line reads hundredths digit 6, 5 or more, so round up. The last step shows 6.97.
See the whole ideathe big idea and the key word, in one place
The big idea
Rounding up from 2.9 makes 10 tenths, a new whole: 2.96 rounds up to 3.0.
Across a whole
1.98 rounds to 2.0. 2.96 rounds to 3.0. 6.97 rounds to 7.0.
- 1.982.0
- 2.963.0
- 6.977.0
Easy to get wrongAfter 9 tenths there is no “10 tenths” place. The ones digit goes up by 1 and the tenths become 0.
Key words
- round up
- move to the greater neighbour
- round down
- move to the smaller neighbour
Ready to use it?
- Round a decimal up across a whole number.
- Write a rounded tenth with its zero.