Karmandir 
About
The Guru Yantra is the number yantra of Brihaspati, also called Guru, the teacher of the devtas. Its nine numbers run from 5 to 13, the Surya square with 4 added to each, so every row, every column and both diagonals add up to 27, with 9 in the middle. In the full Navagraha Yantra, Guru's square sits on the north side, the place the Matsya Purana gives him. Families keep it in the puja place and remember Brihaspati dev on Thursdays with his verse from the Navagraha Stotram, which calls him golden in colour and the very form of wisdom.
Parts of the yantra
Number square: nine cells, written in Devanagari digits in the drawing — top row 10, 5, 12; middle row 11, 9, 7; bottom row 6, 13, 8. Every row, column and diagonal totals 27, and 9 sits in the middle cell. Any two numbers facing each other across the middle always add up to 18. Lines: a gold outer line closes the square and saffron lines divide it into nine cells. Frame: a plain border of three lines around the square, marking the yantra's space.
How to use it
Place the yantra upright on a clean cloth in the puja place. On a Thursday, or on any day, light a diya, offer a flower and sit quietly facing it. Rest your eyes first on the middle number, 9, then move them through the numbers from 5 up to 13, one cell at a time; this gives the mind one calm thing to follow. Then read Brihaspati dev's verse from the Navagraha Stotram (देवानां च ऋषीणां…) once, or 11 times. Wipe the yantra with a soft, dry cloth to keep it clean.
देवानां च ऋषीणां च गुरुं काञ्चनसंनिभम्। बुद्धिभूतं त्रिलोकेशं तं नमामि बृहस्पतिम्॥
Devanam Cha Rishinam Cha Gurum Kanchana Sannibham. →
Frames differ from print to print: the NCERT figure, for example, draws this square inside a square frame with marks at the corners. Many prints use the digits 1, 2, 3 instead of the Devanagari digits used here. The numbers and their places stay the same.
