Adding and Subtracting: Estimate by rounding each number to the highest COMMON place value. Basically round both numbers to the biggest place value that they BOTH have.
ex: 17.92 + 182.034
since both numbers have a digit in the tens place (underlined), we would round to the tens.
20 + 180 = 200
Multiplying: Estimate by rounding EACH number to its OWN highest place value. Basically, use as many zeros as possible!
ex: 5.67 x 41.08376
round the first number to the ones place and the second number to the tens place
6 x 40 = 240
Dividing: Estimate by using compatible numbers. Round the divisor first and then search for a compatible number for the dividend.
ex: 41.03 / 7.15
round the 7.15 to 7 and then think about multiples of 7. Since 42 is a multiple of 7 and is reasonably close to 41.03, we round it to 42.
42 / 7 = 6
Tomorrow we will have a short graded class assignment. You should know the following topics to be ready to do awesome on the graded class assignment:
- Writing decimals in word form and number form.
- example: thirty and seventy-two tenths = 30.72
- Representing a decimal value on a grid.
- Basic estimating strategies with decimals
- Round decimal values.
- Comparing and ordering decimal values.
Have a good night!
-Miss K :)