Mental Calculation - Tips & Tricks

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Mental math Tips: Addition ▫ Subtraction ▫ Multiplication ▫ Division ▫ Sine ▫ Cosine ▫ Tangent

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MENTAL MATH: TiPs & TrIcKs for...

Division I

Dividing is quite simple, the main key to agility when it comes to solving such operations is knowing the basic divisibility rules of numbers from 2 to 10.

Dividing by 2: if it's an even number.
24 ÷ 2 = 12
12486 ÷ 2 = 6,243

Dividing by 3: if the sum of all digits is divisible by three, the number is too.
27 ÷ 3 = 9 (2 + 7 = 9)
18462 ÷ 3 = 6,154 (1+8+4+6+2=21)

Dividing by 4: if the number composed by the last two digits are divisible by 4, the original number will be as well.
324 ÷ 4 = 82 (24 ÷ 4 = 6)
38,712 ÷ 4 = 9,678 (12 ÷ 4 = 3)

Dividing by 5: if it ends in 5 or 0.
105 ÷ 5 = 11
46,800 ÷ 5 = 9,360

Dividing by 6: if the number is divisible by 2 and 3 it is by 6 as well.
378 ÷ 6 = 63
120,540 ÷ 6 = 20,090

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