You should know the number of days of each month.
The next thing you should is to count the months by the knuckles with the closed fist. Every knuckle and every cleft between them is a month. The month has 31 days if the moth falls on knuckle, and the month has 30 or less if it falls into a cleft.
Determine the time before the sunset.
Place the fingers together and then stretch the hand so that the sun is on the index finger. Count the number of your fingers to the horizon, remember that every 15 min of the sunset are presented by each finger.
Waxing crescent moon?
To know in which phase the moon compares it with the letters D, C, and O. Moon D is increasing, O is full Moon and C is waning.
Nemotechnique to learn Roman numerals
Use the following phrase: LaCa De Mamá. The letters L, C, D, M represent the numbers 50, 100, 150, and 200 respectively.
Check the charge of a battery
Raise the battery to 1 or 2 cm on a table and then let it fall. It has no load if it staggers and falls.
The 9 Table with Hands
Put the hands with the palms towards you. Assign to each finger of your left hand a number, from one to five, starting with your little finger; and from six to ten to each finger of the right hand starting with your thumb. Now, to multiply, for example, 9 × 7, lower the assigned finger with the number 7; the number of fingers remaining to the left of that finger will be tens, and the number of fingers to the right units. In the example, 9 × 7 = 63.
Notes on the staff
To remember the location of the notes memorize the following sentences. For notes on the lines: MY SUN IS ALWAYS REPEAT FAULUS. For notes in the spaces between the lines: FAbrica LA DOrada MIel.
The order of the planets
It is enough to remember the following phrase and use it as a mnemonic resource: “My Old Aunt Marta Never Knew Nothing to the Bread”; Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto.