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Addition word problem: starfish

Sal solves a word problem with the term "fewer".

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  • hopper cool style avatar for user Dane
    what does he mean in ?
    (3 votes)
    • stelly blue style avatar for user Radiant Rabbit
      @Is Sal

      Hi there! Let's walk through the steps together to see if this helps:


      Steps are below:

      1) We want to add 59 and 28
      2) Begin by adding 9 and 8 which are located in the ones place. Because 9 + 8 = 17 we need to carry the 7 down to the ones place and 1 to the tens place above the other tens known in this problem as 5 and 2
      3) Now we can add all the numbers in the tens place. Those numbers are 1, 5, and 2. The total should be 8
      4) Then we can bring 8 down to the tens place in front of its friend 7
      5) Last, you have your answer :)! Our answer is 87.

      8 is in the tens place and 7 is in the ones place.

      Please let me know if you need help with a different topic discussed in this video. Good question Is Sal

      You can learn anything,

      Fellow Khan Academy student <3
      (9 votes)

Video transcript

- [Voiceover] Jacques took a submarine to the bottom of the ocean and discovered an underwater city. The starfish ruled the city. This is fascinating. There were 59 seahorses there, which was 28 fewer than the number of starfish. 28 fewer than the number-- I already used that color. Than the number of starfish. How many starfish, how many starfish were there? So let's think about this second sentence, here. So, number of seahorses is 28 fewer than the number of starfish. So we could write, we could write, number of seahorses, seahorses, is 28 fewer than the number of starfish. So that means that this is going to be equal to then number of starfish. Number of starfish, starfish minus 28. 28 fewer than the number of starfish. So, let me write that in blue. So, if I have the number of starfish, and I go 28 fewer than that, that's going to be the number of seahorses. That's what they tell us. The number of seahorses. "There were 59 seahorses there, "which was 28 fewer than the number of starfish." And, they actually tell us what the number of seahorses is. It's 59, so we could write this as-- We could write this as, 59 is equal to the number of starfish. Number, actually maybe I'll just draw-- well I'll write it out, starfish. The number of starfish minus 28. Minus 28. Or, another way to think about it is there's 28 more starfish than seahorses. So we could rewrite this as saying, well whatever the number of seahorses are, whatever the number of seahorses are, they tell us, there's 59 seahorses. There's going to be 28 more. There's going to be 28 more starfish. Whenever you do a problem like this, it's always a good idea just to do a check. Just to say, "Okay, are there going to be more "starfish or more seahorses?" And when you look at the information they give us, they say they there are 59 seahorses which was 28 fewer than the number of starfish. So, if there are fewer seahorses than starfish, that tells you there's going to be more starfish. So it makes sense. If you want to go from the seahorses, the number of seahorses to the number of starfish, you would add 28 because there is more starfish than seahorses. So now we just have to figure out what 59 plus 28 is, so let's do that. So, 59 is five 10s, and nine, ones. 28, let's write the two 10s in the 10s place, and the eight ones, in the one's place. We're adding. We're going to go from the number of seahorses add 28 more than that to get to the number of starfish. So let's first go to the one's place. Nine ones, plus eight ones is 17 ones. Write the seven ones, and one 10, or you could think of it as I carried the one. But all I did was I wrote the one 10 in 17, I wrote that in the ten's place. And now I could add one 10, plus five 10, plus two 10s. So let's see. One, plus five, plus two is eight. Eight tens. So the number of starfish is 87. And you should always see if that makes sense. The number of starfish is, this right over here, is 87. So, if there are 59 seahorses, is that 28 fewer than 87? Sure, it is. It's exactly 28 fewer. Like, that's what we used to solve this question.