Math Tricks for Number Theory

Finda Dwi Permatahati (110210101011)

Dini Mustika Sari (110210101013)

Fajri Maulana (110210101014)

Multiplication by 25

24 x 25 =

?: 4 = 6 x 100 = 600

Multiplication by 25

24 x 25 =

: 4 = 6 x 100

24 x 25 =

2425

x 120

+600

= 60048

?

Multiplication by 25

123 x 25 =

? : 4 = 30 x 100

= 3000Remain = 3 x 25

Result =3075= 75

Exercises

4545 x 25 = ?278 x 25 =

?

12

The Uniqueness of Number

92468a7a =

?Can be divided by 9

The Uniqueness of Number

2468a7

2+4+6+8+a+7= 9k

Integer number a+27=

9k a = 0 or a = 9

9

Proof

246807 : 9 = 27423246897 : 9 = 27433

There’s no remain

Exercise

4545450009321

4895p2

12