Expanded Notation

≈ 15 min

Writing a number in expanded notation means splitting it into the value of each digit, added together. It shows the place value out in the open.

3\,726 = 3000 + 700 + 20 + 6

Going the other way — from the parts back to one number — matters just as much: $6000 + 400 + 30 + 2 = 6\,432$ .

Worked example. Expand $4\,209$ .

So $4\,209 = 4000 + 200 + 9$ .

Write $6000 + 400 + 30 + 2$ as a single number.

Which is the correct expanded form of $2\,508$ ?

$2000 + 500 + 8$

$2000 + 50 + 8$

$2000 + 500 + 80$

$200 + 50 + 8$

Fill in the missing part: $7\,049 = 7000 + 40 + \;?$

Using each of the digits $3$ , $1$ , $7$ and $5$ exactly once, what is the largest four-digit number you can build?