Number Theory · Guided Practice

Number Theory

16 questions with answers and video solutions. Try each one before revealing the answer.

1
Use the Euclidean algorithm to find the greatest common divisor of 98\displaystyle 98 and 35.\displaystyle 35.
2
Use Euclid's algorithm to find the highest common factor of 714\displaystyle 714 and 221.\displaystyle 221.
3
Find integers a\displaystyle a and b\displaystyle b such that 319a+132b=11.\displaystyle 319a+132b=11.
4
Show that the greatest common divisor of 133\displaystyle 133 and 612\displaystyle 612 is 1.\displaystyle 1.
Hence find x,yZ\displaystyle x, y \in \mathbb Z such that 133x+612y=1.\displaystyle 133x+612y=1.
5
Convert the decimal number 3508\displaystyle 3508 into base 7.\displaystyle 7.
6
Use the division algorithm to convert 70549\displaystyle 7054_{9} into base 8.\displaystyle 8.
7
2023 P2 Q6
(1, 2, 1)4 Marks

(a)Use the Euclidean algorithm to find d\displaystyle d, the greatest common divisor of 703 and 399.

(b)Find integers a\displaystyle a and b\displaystyle b such that d=703a+399b.\displaystyle d=703a+399b.

(c)Hence find integers p\displaystyle p and q\displaystyle q such that 76=703p+399q.\displaystyle 76=703p+399q.

8
2017 Q8
4 Marks

Use the Euclidean algorithm to find integers a\displaystyle a and b\displaystyle b such that 1595a+1218b=29.\displaystyle 1595a + 1218b = 29.

9
2018 Q5
4 Marks

Use the Euclidean algorithm to find integers a\displaystyle a and b\displaystyle b such that 306a+119b=17.\displaystyle 306a + 119b = 17.

10
2022 P2 Q3
3 Marks

Use the Euclidean algorithm to find integers a\displaystyle a and b\displaystyle b such that 634a+87b=1.\displaystyle 634a+87b=1.

11
2024 P2 Q2
3 Marks

Use the Euclidean algorithm to find integers a\displaystyle a and b\displaystyle b such that 533a+455b=13.\displaystyle 533a + 455b = 13.

12
2019 Q12
3 Marks

Express 23111\displaystyle 231_{11} in base 7.

13
2023 P2 Q9
2 Marks

Express 57210\displaystyle 572_{10} in base 9.

14
2025 P2 Q4
(1, 2)3 Marks

(a)Use the Euclidean algorithm to find d\displaystyle d, the greatest common divisor of 1118 and 416.

(b)Hence find integers a\displaystyle a and b\displaystyle b such that 1118a+416b=d.\displaystyle 1118a + 416b = d.

15
2026 P2 Q4
(1, 2)3 Marks

(a)Use the Euclidean algorithm to find d\displaystyle d, the greatest common divisor of 1428 and 567.

(b)Find integers a\displaystyle a and b\displaystyle b such that 1428a+567b=d.\displaystyle 1428a+567b=d.

16
2026 P2 Q9
3 Marks

Express 34425\displaystyle 3442_{5} in base 9.

Practice questions courtesy of Maths.scot. Full written solutions are on his site — the links above go straight to them.