Line up the decimal points so each place sits above the same place. Write zeros to fill empty places: 4.5 + 2.37 is 4.50 + 2.37 = 6.87.
Worked example
Find 19.4 − 7.8. Line up the decimal points.
Answer:11.6
Line up the decimal points and write zeros so both numbers have 1 decimal place: 19.4 − 7.8. Subtract from the right, regrouping when you need to. Answer: 11.6.
For grown-ups: Fluent decimal operations, standard algorithms. Below: three problems to try with the worked answers, and a free printable sheet. Children can practise the same skill as a game, with no sign-up and no ads.
CCSS 6.NS.B.3
What this practises, for teachers
Practices fluent decimal operations, standard algorithms (6.NS.B.3). A printable sheet with its answer key, worked answers on the page, no accounts.
Line up the decimal points and write zeros so both numbers have 1 decimal place: 19.4 − 2.3. Subtract from the right, regrouping when you need to. Answer: 17.1.
Find 48.75 + 49.85. Line up the decimal points.
Show the answer and how
Answer:98.6
Line up the decimal points and write zeros so both numbers have 2 decimal places: 48.75 + 49.85. Add from the right, regrouping when you need to. Answer: 98.6.
Find 44.9 − 23.99. Line up the decimal points.
Show the answer and how
Answer:20.91
Line up the decimal points and write zeros so both numbers have 2 decimal places: 44.90 − 23.99. Subtract from the right, regrouping when you need to. Answer: 20.91.