Summary - Numbers and Math

Build a dice roll simulation using Math methods.

Summary - Numbers and Math

In this group you met JavaScript's single number type, number; integers and decimals live in the same type.

The Math object gives rounding and randomness: Math.round goes to the nearest, Math.floor down, Math.ceil up; Math.random produces a random 0-1 value; Math.min and Math.max pick the smallest and largest.

To convert to a number you use parseInt (with radix 10), parseFloat and Number. Edge cases show as NaN and Infinity; you test both safely with Number.isNaN and Number.isFinite.

Exercise Parse two prices, round, find the larger

Assign parseFloat("19.49") to priceA and parseFloat("25.99") to priceB. Put Math.round(priceA) and Math.round(priceB) into rA and rB. Then put Math.max(rA, rB) into larger and log larger with console.log.

Show example solution

const priceA = parseFloat("19.49");
const priceB = parseFloat("25.99");
const rA = Math.round(priceA);
const rB = Math.round(priceB);
const larger = Math.max(rA, rB);
console.log(larger);

Exercise Roll two dice, find the smaller

Assign Math.floor(Math.random() * 6) + 1 to roll1 and roll2. Then use Math.min to put the smaller roll into smaller and log smaller with console.log.

Show example solution

const roll1 = Math.floor(Math.random() * 6) + 1;
const roll2 = Math.floor(Math.random() * 6) + 1;
const smaller = Math.min(roll1, roll2);
console.log(smaller);

Test yourself

Match each method to its job

Math.round

Nearest whole number
Math.floor

Down to whole number
parseInt

Parses string to integer
Math.random

Random 0 to 1 value
What does parseInt("100", 2) return?
```
console.log(parseInt("100", 2));
```
- 100
- 4
- 2
- NaN
Show answer

4 — Correct. Radix 2 means binary; "100" in binary equals 4.

Next lesson: Project: Calculator

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