1.1.5Arithmetic & Number Systems

Division — long division, remainder, dividend - divisor - quotient vocabulary

1,644 words7 min readdifficulty · medium

WHAT: The vocabulary


HOW: Long division, derived step-by-step

Long division is the division algorithm applied one place-value column at a time, from the biggest place down. Because a number like 728728 means 7 hundreds+2 tens+8 ones7\text{ hundreds}+2\text{ tens}+8\text{ ones}, we divide the hundreds first, carry the leftover into the tens, and so on.

Figure — Division — long division, remainder, dividend - divisor - quotient vocabulary

Forecast-then-Verify drill


Common mistakes (Steel-manned)


Divisibility shortcut (80/20)


Recall Feynman: explain to a 12-year-old

Imagine sharing 728728 marbles into 66 boxes. First deal out the big bags of 100: you can put 11 hundred in each box (66 hundreds used), 11 hundred left. Break that leftover hundred into tens, mix with the tens you had, deal those out, then do the same with the single marbles. Whatever marbles you can't deal evenly are the remainder. The number each box gets is the quotient, the pile you started with is the dividend, and the number of boxes is the divisor.


Flashcards

Name the four division words in a÷b=qa \div b = q rem rr.
aa=dividend, bb=divisor, qq=quotient, rr=remainder.
State the Division Algorithm equation.
Dividend == Divisor ×\times Quotient ++ Remainder, with 0r<0\le r< divisor.
Why must the remainder be smaller than the divisor?
If rr\ge divisor, another whole group fits, so the quotient wasn't complete.
In 728÷6728\div6, what are quotient and remainder?
Quotient 121121, remainder 22 (since 6×121+2=7286\times121+2=728).
The 4 repeating long-division steps?
Divide, Multiply, Subtract, Bring down (DMSB).
How do you check any long-division answer?
Compute divisor×\timesquotient++remainder; it should equal the dividend.
When do you write a 00 in the quotient?
When, after bringing down a digit, the running number is still smaller than the divisor.
Remainder =0=0 tells you what?
The divisor divides the dividend exactly (dividend is a multiple of divisor).
Digit-sum rule: why does it test divisibility by 3?
Because 101(mod3)10\equiv1\pmod3, a number and its digit sum share the same remainder mod 3.

Connections

Concept Map

is

counts

leftover is

divided by

fits q times

and ALG

must satisfy

applied per column

uses

verifies

Division = share into equal groups

Repeated subtraction of divisor

Dividend - whole amount

Divisor - group size

Quotient - number of groups

Remainder - what is left

Division Algorithm a = dq + r

0 le remainder less than divisor

Long division, column by column

Place value, bring down trick

Check by multiplying back

Hinglish (regional understanding)

Intuition Hinglish mein samjho

Division ka matlab simple hai: ek badi cheez ko barabar groups mein baantna aur dekhna ki kitna bacha. Jaise 728728 marbles ko 66 boxes mein daalna. Yaha 728728 hai dividend (jise baant rahe ho), 66 hai divisor (kitne groups), har box mein jitne jaate hain wo quotient, aur jo bach jaata hai wo remainder. Ek golden rule yaad rakho: remainder hamesha divisor se chhota hona chahiye — agar barabar ya bada ho gaya, matlab ek aur group ban sakta tha, quotient galat hai.

Long division bas ek organised tareeka hai place-value ke hisaab se — pehle hundreds, phir tens, phir ones. Har digit pe wahi 4 steps chalao: Divide, Multiply, Subtract, Bring down (yaad rakho "Does McDonald's Sell Burgers"). Jab ek digit neeche laao aur number abhi bhi divisor se chhota ho, to quotient mein 00 likhna mat bhoolna — ye sabse common galti hai jaise 308÷4=77308\div4=77 mein pehle 00 ka dhyaan.

Sabse important habit: answer ko verify karo master formula se — Dividend == Divisor ×\times Quotient ++ Remainder. 6×121+2=7286\times121+2=728, bilkul sahi. Aur agar remainder 00 aaye, iska matlab divisor number ko poori tarah divide karta hai (exactly divisible). Exam mein pehle estimate karo (forecast), jaise 623÷8623\div8 ka answer 7070s mein hoga — isse chhoti-chhoti calculation mistakes turant pakad mein aa jaati hain. Ye chapter aage fractions, HCF-LCM aur remainders (modular arithmetic) ki neev hai.

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Connections