All the Digits

The whole calculation uses each of the digits 0-9 once and once only. How many solutions can you find?
reference: NRICH
[url=https://nrich.maths.org/1129]https://nrich.maths.org/1129[/url]
Using each of the numbers 1 to 9 once and once only, find two numbers, one of which is double the other. How many solutions can you find?
reference: NRICH
[url=https://nrich.maths.org/7182]https://nrich.maths.org/7182[/url]
– spkwan

Information: All the Digits