Good question, with no single right answer for every child. Here are some points to consider:

• Schools and teachers need to find out what their curriculum requires. In broad terms, the US and Australian curricula require all student to know up to 10x tables. The UK curriculum requires tables to be known to 12x. Teachers and schools will generally stick with the guideline minimum standards on that front.
• It is important to think about why a student would need to know beyond the 10x number facts. Looking through history it is easy to see why 12x number facts were essential: 12 inches in a foot, 12 pennies in a shilling. With metric measures (based on 10, 100, 1000, etc.) becoming the standard the world over, is it necessary any more?
• Some say 12x facts extend the mind. Fair enough, but why stop at 12x? Why not go for 13x, 14x, etc.?
• One line of argument is based on tradition: I learned it at school, so my child should do so too. You will have to decide if that is important to you.
• Dozens are a very common multiple and are still used, partly because 12 items can be arranged in 3 rows of 4, which saves on packaging compared to 2 row of 5, if we were to pack things in tens.
• Learning the 11x and 12x tables increases the number of facts to be committed to memory by 44%, compared to 1x-10x. Is it really worth that effort?
• 10x is essential for multiplication algorithms (sums) but 12x is not.
• 12x tables help with knowing hours in a day, and 360 degrees in a circle.
• If number facts are learned with strategies, students can work out the 12x answers (6x12 is the same as 6x10 + 6x2). Why the need to commit them to memory any more than 15x or 18x?

Because of different preferences and curriculum requirements, eBooks in our Number Fluency "Times Tables" Series which cover multiplication or division offer both versions, the 10x and the 12x. Make sure you choose the version you or your school prefer when you go to our store.