Unit 2 · Number Theory
Multiples Under 50 — Largest Minus Smallest
Lesson 6 of 18
Premium
About this lesson
Number-theory questions often start with listing multiples in a range — write the valid set for each person before you compare or combine them.
Chapters
0:00Introduction
0:22The Question
1:04Finding Morgan's Largest Number
1:30Finding Riley's Smallest Number
2:00Calculating the Target Difference
2:21Exam Strategy — The Dual-Constraint Check
2:54Confirming the Final Option
Question
Morgan and Riley each think of a different whole number.
Each number is greater than zero and less than 50.
- Morgan’s number is a multiple of 4.
- Riley’s number is an odd number that is a multiple of 3.
What is the difference between the largest possible value of Morgan’s number and the smallest possible value of Riley’s number?
Free account · Selective
Take your Selective prep further
- Sample questions & worked solutions across core Selective topics
- Digital exam simulator with interactive practice sets
- Personalised progress tracking across all your devices
Already have an account? Log in here
No payment required. Compare Selective plans
Give Your Child the Best Chance at Selective Entry
Join NSW families preparing their children for the Selective Schools Placement Test with the most realistic online Selective practice tests available. First tests free—no credit card required.
Claim Your Free Selective Practice Tests