If the world was ending [としたら]

We can use としたら to  talk about hypothetical situations.

もし今日きょうで世界せかいが終おわるとしたら、私わたしの最後さいごの食事しょくじはお寿司すしに間違まちがいない。

If the world was going to end today, My last meal would be definitely by sushi.

Structure

するとしたら、したとしたら (Verb casual)

だとしたら、だったとしたら (noun +だ)

You can replace としたら withとすれば without changing the meaning although, according to my grammar books, としたら is slightly more casual. We must also be careful to not mix this up with ようとしたら (the violational form of the verb) which means as I was about to do.

Examples

もし君きみが猫ねこになったとしたら、どうする？

If you became a cat, what would you do?

夏なつにイギリスへ行いくとしても、雨あめが降ふるでしょ。

Even supposing we went to England in the summer, It would still rain, wouldn’t it?

In the last example we are using しても to give an even if meaning to the sentence.