
LCM and HCF- Formula Sheet
Definition:
LCM (least Common Multiple): Smallest numbers divisible by given numbers
HCF (Highest common Factor): Greatest number that divides the given numbers
Methods to Find HCF and LCM
- Prime Factorization Method
- Division Method
Important Formula
LCM × HCF = product of two numbers
Fraction Formulas
HCF of Fractions =
LCM of Fractions =
Relation for Two Numbers
If a=LCM, b=HCF
Numbers = a × x , a × y (where x, y are co-prime)
TYPES OF NUMBERS
Natural Numbers: 1, 2, 3, …
Whole Numbers: 0, 1, 2, 3, …
Integers: …… 3, 2, 1, 0, 1, 2, 3, 4……..
Rational Numbers:
(q≠0)
PROPERTIES OF NUMBERS
Commutative Law: a+b=b+a, axb =bxa
Associative Law: (a+b)+c=a+(b+c)
Distributive Law: a(b+c) = ab + ac
IDENTITIES
Additive Identity: a + 0 = a
Multiplicative Identity: a x 1 = a
EVEN & ODD NUMBERS
Even = 2n
Odd = 2n +1
PRIME & COMPOSITE NUMBERS
Prime: exactly two factors (2,3,5,7 … )
Composite: more than two factors
DIVISIBILITY RULES
By 2 last digit even
By 3 sum of digits divisible by 3
By 5 last digit 0 or 5
By 9 sum of digits divisible by 9
MENSURATION & FORMULA SHEET
CUBE
TSA = 6a 2
CSA = 4a 2
Volume = a 3
Diagonal = a3
CUBOID
TSA = 2(lb+bh+hl)
CSA = 2h (l+b)
Volume = l × b ×h
Diagonal = l 2+b 2 +h 2
CYLINDER
TSA = 2πr(h+r)
CSA = 2πrh
Volume = πr2h
CONE
CSA = πrl
TSA = πr (1+r)
Volume = π r2h
l = r2 +h2
SPHERE
TSA = 4πr2
Volume = πr3
SEMISPHERE
TSA = 3πr2
CSA = 2πr2
Volume= πr3
IMPORTANT TRIANGLE FORMULAS
Area = ×b×h
Heron’s Formula = s(s-a)(s-b)(s-c)
CIRCLE FORMULAS
Area = πr2
Circumference = 2πr
Area of semicircle = πr2