Grades 3-4 Video Solutions 2024-2024_3-4

Video Transcription

Question 17. A student has three cards with numbers on them. Their sum is 782.  Unfortunately, a worm ate part of each card. What is the sum of the three missing digits?  Let's start off by drawing the equation as such. We can erase the hundreds and the tens columns,  and that leaves us with the ones column. We have 3 plus 4 plus an unknown equal to 2.  And to solve this, we do not actually have to have these equal to 2. It's equal to a number  that ends in 2. In this case, we have 3 and 4, which equals 7. And if we add 5, that gives us 12.  This means that we can leave the 2 here and carry over the tens digit 1 over to the next column,  where we will have 1 plus a number plus a number plus 1 equal to 8. Here, we could do the same  thing, either having this number end up being 8 or 18. Now let's check the hundreds column,  where we have 2, 1, and 4, which gives us 7. That means we cannot add in the second column  a hundreds digit. So that means we will have to end up with 8. To end up with 8, those two unknown numbers will have to have a sum of 6. Does not matter how that is calculated.  So to get our answer, the sum of the three missing digits will have 5 plus 6,  which will give us our answer, which will be d, 11.

Video Summary

A student has three cards, each partially damaged and missing digits, with a total sum of 782. Solving for the missing digits involves calculations in each column, ensuring the numbers fit the required sums. The one's column initially appears to sum to 2, but it needs to end in 2, meaning a sum of 12, resulting in a missing digit of 5. Moreover, the tens column requires missing digits summing to 6 to reach a plausible total of 8. Adding these missing parts, 5 and 6, gives the total sum of the missing digits, which is 11.

Keywords

missing digits

sum of 782

column calculations

missing parts

digit puzzle