Grades 9-10 Video Solutions 2022-2022_9-10

Video Transcription

Question 1. Carolyn is forming the four-digit number 2022 using some matches from a box.  The box originally contained 30 matches. She has already started and formed the first two digits as shown in the diagram.  How many matches will remain in the box when she has finished forming 2022?  So if we take a look at the matches that we have already made, we see 20. Now we will just need to repeat two more twos, like so.  Now we can count up the amount of matches that each digit takes. So the 2 takes 5, the 0 takes 6, and then there are two more twos, which will take 5 each.  If we take the sum of 5, 6, 5, and 5, we get 21. The box originally contained 30 matches, so we will do 30 minus 21 to get our solution, which will be D, 9.

Video Summary

Carolyn is forming the number 2022 using matches. The box initially held 30 matches. She's already formed "20", using five matches for the '2' and six matches for the '0'. She will need two more '2's, each requiring five matches. Calculating the total, 5 (first '2') + 6 ('0') + 5 (second '2') + 5 (third '2') amounts to 21 matches. Subtracting this from the original 30 matches, Carolyn will have 9 matches remaining once she's finished forming the number 2022.

Keywords

matches

number formation

2022

remaining matches

calculation