Will this method work if the units digit is 0? What do you think? What other methods can you use to find the missing number to fill in the blanks?
Yes, the method works even if the units digit is 0.
Example: 180 + 820 = 1,000
The method of finding complements to 100 or 1,000 works for all numbers.
Alternative Methods:
Method 1: Direct subtraction 1,000 - 180 = 820
Method 2: Mental math by place value Find what makes each place value add up to the target.
Explanation
The chapter encourages students to think about whether the complement method works universally. Students can discuss alternative strategies like direct subtraction or place value analysis.
Solution Steps
The complement method works for all numbers, including those with units digit 0.
Example verification: 180 + 820 = 1,000
Alternative Method 1: Use direct subtraction (1,000 - 180 = 820) to find the missing number.
Alternative Method 2: Use mental math by analyzing each place value to find what adds up to the target.