Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Rounding makes a number simpler while keeping its value close to the original.
The Target Digit is the digit in the place value you are rounding to (e.g., the Tens place).
The Deciding Digit is the digit immediately to the right of the target digit.
The '5 or More' Rule: If the deciding digit is 5, 6, 7, 8, or 9, increase the target digit by 1.
The '4 or Less' Rule: If the deciding digit is 0, 1, 2, 3, or 4, the target digit stays the same.
Placeholders: All digits to the right of the rounded place must be changed to zeros.
📐Formulae
💡Examples
Problem 1:
Round 86 to the nearest 10.
Solution:
90
Explanation:
The target digit is 8 (tens). The digit to the right is 6. Since 6 is '5 or more', we round the 8 up to 9 and change the units to 0.
Problem 2:
Round 432 to the nearest 100.
Solution:
400
Explanation:
The target digit is 4 (hundreds). The digit to the right is 3. Since 3 is '4 or less', the 4 stays the same. Change all digits to the right to 0.
Problem 3:
Round 7,500 to the nearest 1,000.
Solution:
8,000
Explanation:
The target digit is 7 (thousands). The digit to the right is 5. According to the rule, 5 means we round up. 7 becomes 8, and the rest become zeros.
Problem 4:
Round 24,999 to the nearest 10,000.
Solution:
20,000
Explanation:
The target digit is 2 (ten-thousands). The digit to the right is 4. Since 4 is '4 or less', the 2 stays the same. All digits to the right (4, 9, 9, 9) become 0.