How to make a 照片 black and white without PhotoShop?

Hi - So I was trying to print the same picture twice on one page (one in colour and one in black and white) - but I don't know how to make a black and white version - I don't have PhotoShop - only basic computer programs. I can of course, print it out twice but it only takes up half a page and would be wasting paper - plus I have 更多 pictures that I need to do it with too. Any help would be welcome - thanks in advance :)