Math Tricks for Number Theory

Finda Dwi Permatahati (110210101011)

Dini Mustika Sari (110210101013)

Fajri Maulana (110210101014)

Multiplication by 25

24 x 25 =

?

: 4 = 6

= 600= 6 x 100

1

2

Comparing two methods24 x 25 =: 4 = 6

24 x 25 =

2425

x 120

+600 = 60048

?= 6 x 100

1

2

Multiplication by 25

123 x 25 =

?

: 4 = 30, remain=3

= (30 x 100) + (3 x 25)= 3000 + 75= 3075

1

2

Exercises

4545 x 25 = ?278 x 25 =

?

12

The Uniqueness of Number

918 is multiple of 927 is multiple of 936 is multiple of 9

1 + 8 = 92 + 7 = 93 + 6 = 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

24376p

12