Random whole numbers with ROUND and RANDOM

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Quick Questions

Shade in the A or B circle for each question.

1. Which expression gives a random whole number from 0 to 6?

A ROUND(RANDOM() * 6, 0)

B RANDOM() * 6

2. What does RANDOM() give on its own?

A A whole number from 1 to 6

B A decimal from 0 to 1

3. Which line stores a random whole number from 0 to 10?

A Value ← ROUND(RANDOM() * 10, 0)

B Value ← ROUND(RANDOM(), 10)

4. In ROUND(RANDOM() * 6, 0), what does the 0 mean?

A The smallest number that can be picked

B Round to 0 decimal places, so a whole number

5. Which expression gives a random whole number from 1 to 7?

A ROUND(RANDOM() * 6, 0) + 1

B ROUND(RANDOM() * 6, 0) * 1

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1Value ← ROUND(RANDOM() * 6, 0)		AFUNCTION RollDie() RETURNS INTEGER RETURN ROUND(RANDOM() * 5, 0) + 1 ENDFUNCTION
2Roll ← ROUND(RANDOM() * 5, 0) + 1		BROUND(RANDOM() * 10, 0)
3Nesting one routine inside another: RANDOM() is called inside ROUND() to get a whole number		CStores a random whole number from 0 to 6 in the variable Value
4A function that returns a die roll from 1 to 6		DStores a random whole number from 1 to 6, like a die roll
5Value ← ROUND(RANDOM(), 0) * 6		EThis gives 1 to 7, not 1 to 6, because the range 0 to 6 has 7 values and adding 1 shifts it to 7. To roll a die, multiply by 5 instead: ROUND(RANDOM() * 5, 0) + 1.
6Roll ← ROUND(RANDOM() * 6, 0) + 1		FROUND is applied before multiplying. RANDOM() is a decimal from 0 to 1, so it rounds to only 0 or 1, giving just 0 or 6. The multiplication should be inside ROUND: ROUND(RANDOM() * 6, 0).

Definitions

ROUND(RANDOM() * 6, 0)

Fill in the Blanks

Complete each line of code by filling in the missing parts.

Value ← ROUND(______() * 6, 0)

// random whole number 0 to 10 Value ← ROUND(RANDOM() * __, 0)

// random whole number 1 to 6 Value ← ROUND(RANDOM() * 5, 0) + _

FUNCTION RollDie() RETURNS INTEGER RETURN ROUND(RANDOM() * 5, _) + 1 ENDFUNCTION

Value ← _____(RANDOM() * 6, 0)

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A DECLARE Roll : INTEGER

B Roll ← ROUND(RANDOM() * 6)

C OUTPUT Roll

Question 2

A FUNCTION Die() RETURNS INTEGER

B DECLARE N : INTEGER

C N ← ROUND(RANDOM()*5, 0) + 1

D OUTPUT N

E ENDFUNCTION

Question 3

A DECLARE Dice : INTEGER

B Dice ← ROUND(RANDOM() * 5, 0)

C Dice ← Dice * 1

D OUTPUT Dice

Question 4

A Roll ← ROUND(RANDOM * 6, 0)

B Bonus ← Roll * 10

C OUTPUT Bonus

Question 5

A Num ← ROUND(RANDOM(), 0) * 10

B OUTPUT "Number: ", Num

C OUTPUT "Max is 10"

Answer Key

Random whole numbers with ROUND and RANDOM

Section A: Quick Questions

A — ROUND(RANDOM() * 6, 0)

B — A decimal from 0 to 1

A — Value ← ROUND(RANDOM() * 10, 0)

B — Round to 0 decimal places, so a whole number

A — ROUND(RANDOM() * 6, 0) + 1

Section B: Match the Pairs

Value ← ROUND(RANDOM() * 6, 0) → Stores a random whole number from 0 to 6 in the variable Value

Roll ← ROUND(RANDOM() * 5, 0) + 1 → Stores a random whole number from 1 to 6, like a die roll

Nesting one routine inside another: RANDOM() is called inside ROUND() to get a whole number → ROUND(RANDOM() * 10, 0)

A function that returns a die roll from 1 to 6 → FUNCTION RollDie() RETURNS INTEGER RETURN ROUND(RANDOM() * 5, 0) + 1 ENDFUNCTION

Value ← ROUND(RANDOM(), 0) * 6 → ROUND is applied before multiplying. RANDOM() is a decimal from 0 to 1, so it rounds to only 0 or 1, giving just 0 or 6. The multiplication should be inside ROUND: ROUND(RANDOM() * 6, 0).

Roll ← ROUND(RANDOM() * 6, 0) + 1 → This gives 1 to 7, not 1 to 6, because the range 0 to 6 has 7 values and adding 1 shifts it to 7. To roll a die, multiply by 5 instead: ROUND(RANDOM() * 5, 0) + 1.

Section C: Definitions

ROUND(RANDOM() * 6, 0) — Gives a random whole number from 0 to 6. RANDOM() gives a decimal from 0 to 1, times 6 stretches it, and ROUND(..., 0) turns it into a whole number.

Section D: Fill in the Blanks

Value ← ROUND(RANDOM() * 6, 0)

// random whole number 0 to 10
Value ← ROUND(RANDOM() * 10, 0)

// random whole number 1 to 6
Value ← ROUND(RANDOM() * 5, 0) + 1

FUNCTION RollDie() RETURNS INTEGER
  RETURN ROUND(RANDOM() * 5, 0) + 1
ENDFUNCTION

Value ← ROUND(RANDOM() * 6, 0)

Section E: Spot the Error

B — ROUND needs a second argument saying how many decimal places to keep. For a whole number it must be ROUND(RANDOM() * 6, 0).

D — A function must pass its result back to the caller with RETURN. OUTPUT only displays the value, so line 4 should be RETURN N.

C — To move the range from 0 to 5 up to 1 to 6 you must add 1. Multiplying by 1 changes nothing. It should be Dice ← Dice + 1.

A — RANDOM is a library routine, so it needs brackets when it is called. It should be RANDOM(), giving ROUND(RANDOM() * 6, 0).

A — The multiplication must happen before rounding. Here RANDOM() is rounded first to 0 or 1, so the result is only 0 or 10. It should be ROUND(RANDOM() * 10, 0).