0.25+0.27
When the fractional parts, if any, of the two decimal numbers sum to 1.
First, round the highest place value of each number: 400+200+700=1300 Second, round the second highest place value of each number: 390+190+740=1320 The range to estimate the sum is 1300 to 1320. The actual sum is 1321, which higher than the range. However, the actual sum may lie within the obtained range. LEF
This will happen if the fractional parts of the numbers sum to 1.
to find a low estimate for the product of two decimals, round both factors
It depends on your level of numerical skill. You can convert the decimal to an approximate fraction and estimate the sum of the two fractions, or you can convert the fraction to an approximate decimal and estimate the sum of the two decimals or, if you are more able you just estimate their sum directly.
The range of a single number - with or without a decimal - is zero.
The same way as whole numbers. 0.3865 + 0.2274 could be estimated as 0.40 + 0.20 = 0.6
Sum is an answer to an addition problem.
0.7 0.5
1,400
between 20 and 30
When the fractional parts, if any, of the two decimal numbers sum to 1.
First, round the highest place value of each number: 400+200+700=1300 Second, round the second highest place value of each number: 390+190+740=1320 The range to estimate the sum is 1300 to 1320. The actual sum is 1321, which higher than the range. However, the actual sum may lie within the obtained range. LEF
The largest value is 17.563 The smallest is 2.31 So the range is 17.563 - 2.31 = 15.253
18.812 and 31.187
Round the highest and lowest numbers. 25 - 5 = 20