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Ordinal Numbers


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Team Digital

Basics on the topic Ordinal Numbers

What are ordinal numbers? How do you write ordinal numbers? Learn all about ordinal numbers with this video.

Transcript Ordinal Numbers

Skylar and Henry have taken part in a competition. They came first and third! However, Skylar and Henry do not know what this means. Let's join in and learn about ordinal numbers. When we say someone came first, fourth, or tenth in a race, we are labeling their position with ordinal numbers. Ordinal numbers describe the order, or position, of numbers. Ordinal numbers are written differently in number form and word form. Ordinal numbers for one, two, and three, are special. When something is in the number one position, this is first, or a one followed by -st. Number two position is second, or a two followed by -nd. And three is third, or a three followed by -rd. The ordinal numbers from four to ten, except for five, end in -th, and sound like the regular number. Four is fourth, or four followed by -th. Five is fifth, where the -ve comes off and we add -fth. What about the number six? Six is sixth, or a six followed by -th. This pattern continues for seven, eight, nine, and ten! Multiples of ten up to one hundred use -th endings, or -ieth if they end in a 'y'. They also sound like their regular numbers. We already know ten, so we can look at the next multiple of ten, twenty. Twenty is twentieth, changing the 'y' to 'i' and add -eth. Thirty becomes thirtieth. Forty becomes fortieth. This pattern continues for fifty, sixty, seventy, eighty, ninety, and one hundred! Every other number in between multiples of ten except for numbers with one, two, three, or five in them have the -th added to the end of the number. Eleven is eleventh. What about the number thirteen? Thirteen is thirteenth. Thirty-six is thirty-sixth. Hyphenated regular numbers keep the first word, and the -th gets added to the last word! What about the number seventy-seven? Seventy-seven is seventy-seventh. Can you write twenty-one in ordinal form? Twenty one becomes twenty-first. Share any other ordinal numbers you can think of in the comments below! Now Skylar and Henry understand the position they finished and are ready to collect their medals, let's review! Remember, ordinal numbers describe the order of numbers. There are some different ways to write ordinal numbers. Numbers one, two, three, and five are special numbers. Multiples of ten up to one hundred have a -th ending, or -ieth if the number ends with a 'y'. Every other number in between these that do not have a one, two, or three in the number all end with -th. Ah, no wonder Skylar won the hopping contest, all thanks to her special frog suit. Cunning as always, Skylar!