Life Skills Arcade Middle school Family and Consumer Sciences, grades 6 to 8

Handout 2.18

Handout 2.18: Return Math

Unit
Unit 2: Me, My Goals, My Money
Lesson
Lesson 2.18: Buying Low Rebalancing and Return Math
File
Handout 02.18 - Return Math.md

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Name: ______________________ Date: __________ Partner (Part C): ______________________

The formula

Percent return = (ending value minus starting value) divided by starting value, times 100.

As a picture: a fraction with "ending minus starting" on top and "starting" on the bottom, then "times 100" beside it. (The slide shows it drawn large with STARTING in bold.)

The bottom of the fraction is always the starting value. If you divide by the ending value, you get the wrong answer every time.

A loss gets a minus sign. A gain gets a plus sign.

Worked example. An investor started with $1,000 in 1870 and has $850 now.

  • Ending minus starting: 850 minus 1,000 = minus 150
  • Divided by starting: minus 150 divided by 1,000 = minus 0.15
  • Times 100: minus 15 percent

The investor's return is minus 15 percent.

Part A: Practice (alone)

Show the subtraction line and the division line for each one. Every price is from the board.

#Starting valueEnding valueEnding minus startingDivided by startingPercent return
1$1,000 (a ledger in 1870)$1,250______ percent
2$1,000 (a ledger in 1870)$850______ percent
3$50 (one share of RAIL in 1870)$30 (1873, the Panic)______ percent
4$60 (one share of OIL in 1911)$70 (1928)______ percent

Grade 6 support rows (round numbers):

#Starting valueEnding valueEnding minus startingDivided by startingPercent return
5$100$120______ percent
6$100$75______ percent
  1. The trick question. GAS was $40 in 1928 (the peak) and $20 in 1932 (the bottom).
  • The drop, as a percent of the peak: (20 minus 40) divided by 40, times 100 = ______ percent
  • The climb back, as a percent of the bottom: (40 minus 20) divided by 20, times 100 = ______ percent
  • Why are the two percents different when the dollar change ($20) is the same both ways? Answer: ______________________________________________________________________

Part B: My own return (alone, from your own ledger)

My starting value, 1870: $1,000

My total right now, at Round 8 (1932) prices: $__________

Ending minus starting: __________

Divided by starting: __________

Times 100: my percent return so far is __________ percent (circle: gain / loss)

Check it on the calculator: __________ Same? yes / no

The company that hurt me most from the peak to the bottom. From your price table: the Round 6 price (1928, the peak) and the Round 8 price (1932, the bottom).

Ticker: ______ 1928 price: $______ 1932 price: $______

(1932 minus 1928) divided by 1928, times 100 = ______ percent

Part C: A safe ledger, a one-company ledger and a mixed ledger over the same rounds (pairs)

Three investors started in 1870 with $1,000, like you, and never traded again. The values below are their totals in three rounds: the peak (Round 6, 1928), the crash (Round 7, October 1929), and the bottom (Round 8, 1932, today). Every value is built from the board's prices and the bank's 3 percent; the teacher key shows how.

  • Safe: all $1,000 in the bank.
  • One company: 20 shares of RAIL at $50 ($1,000), nothing else.
  • Mixed: 5 RAIL at $50 ($250), 25 OIL at $10 ($250), 12 GAS at $20 ($240), and $260 in the bank.
LedgerValue at the peak (1928)Return at the peakValue in the crash (1929)Return in the crashValue at the bottom (1932, today)Return today
Safe$1,195plus 19.5 percent (done for you)$1,231plus 23.1 percent (done for you)$1,268plus 26.8 percent (done for you)
One company$1,400______ percent$900______ percent$200______ percent
Mixed$2,891______ percent$2,179______ percent$1,245______ percent

The Safe row is worked for you as a model. Compute the other six. Round to one decimal place.

  1. Which ledger looked smartest (a) at the peak, (b) in the crash, and (c) today?

(a) ____________________ (b) ____________________ (c) ____________________

  1. Which ledger would you rather have held for these 62 years? Circle one. Then say what it is better for (money for college in ten years, or rent next month) and give a number.

Safe / One company / Mixed. Because: ______________________________________________________________________

More room: ______________________________________________________________________

  1. Grade 8 stretch. The one-company ledger's fall from the peak to the bottom, as a percent of the peak: (200 minus 1,400) divided by 1,400, times 100 = ______ percent. To get back from $200 to $1,400 it must climb: (1,400 minus 200) divided by 200, times 100 = ______ percent. Explain in one sentence why a ledger that fell 86 percent has to climb 600 percent to get back.

My sentence: ______________________________________________________________________


The teacher key for this handout is behind the teacher sign in. Teacher key