NRICH Math Word Problems and Puzzles

From site:  On this website you will find thousands of our free mathematics enrichment materials (problems, articles and games) for teachers and learners from ages 5 to 19 years. All the resources are designed to develop subject knowledge, problem-solving and mathematical thinking skills. The website is updated with new material on the first day of every month. note:  This site is hosted in the United Kingdom.  The problems are sorted by ages, with collections for ages 5-11 and 11-18 the grade levels are shown as “stages.”  Stage 1-2 problems would be for elementary age students in the US.

Each problems gives you a link for hints to solve it.  The solution link will not appear until the following month.